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https://github.com/netwide-assembler/nasm.git
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78abbf26df
Micro-optimize the set_bit() function. Using size_t (in particular, using an unsigned type) produces better code. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
961 lines
28 KiB
C
961 lines
28 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 1996-2020 The NASM Authors - All Rights Reserved
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* See the file AUTHORS included with the NASM distribution for
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* the specific copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following
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* conditions are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* ----------------------------------------------------------------------- */
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/*
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* float.c floating-point constant support for the Netwide Assembler
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*/
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#include "compiler.h"
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#include "nctype.h"
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#include "nasm.h"
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#include "floats.h"
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#include "error.h"
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/*
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* -----------------
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* local variables
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* -----------------
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*/
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static bool daz = false; /* denormals as zero */
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static enum float_round rc = FLOAT_RC_NEAR; /* rounding control */
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/*
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* -----------
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* constants
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* -----------
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*/
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/* "A limb is like a digit but bigger */
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typedef uint32_t fp_limb;
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typedef uint64_t fp_2limb;
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#define LIMB_BITS 32
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#define LIMB_BYTES (LIMB_BITS/8)
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#define LIMB_TOP_BIT ((fp_limb)1 << (LIMB_BITS-1))
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#define LIMB_MASK ((fp_limb)(~0))
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#define LIMB_ALL_BYTES ((fp_limb)0x01010101)
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#define LIMB_BYTE(x) ((x)*LIMB_ALL_BYTES)
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/* 112 bits + 64 bits for accuracy + 16 bits for rounding */
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#define MANT_LIMBS 6
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/* 52 digits fit in 176 bits because 10^53 > 2^176 > 10^52 */
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#define MANT_DIGITS 52
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/* the format and the argument list depend on MANT_LIMBS */
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#define MANT_FMT "%08x_%08x_%08x_%08x_%08x_%08x"
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#define MANT_ARG SOME_ARG(mant, 0)
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#define SOME_ARG(a,i) (a)[(i)+0], (a)[(i)+1], (a)[(i)+2], \
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(a)[(i)+3], (a)[(i)+4], (a)[(i)+5]
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/*
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* ---------------------------------------------------------------------------
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* emit a printf()-like debug message... but only if DEBUG_FLOAT was defined
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* ---------------------------------------------------------------------------
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*/
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#ifdef DEBUG_FLOAT
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#define dprintf(x) printf x
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#else
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#define dprintf(x) do { } while (0)
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#endif
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/*
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* ---------------------------------------------------------------------------
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* multiply
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* ---------------------------------------------------------------------------
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*/
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static int float_multiply(fp_limb *to, fp_limb *from)
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{
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fp_2limb temp[MANT_LIMBS * 2];
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int i, j;
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/*
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* guaranteed that top bit of 'from' is set -- so we only have
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* to worry about _one_ bit shift to the left
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*/
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dprintf(("%s=" MANT_FMT "\n", "mul1", SOME_ARG(to, 0)));
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dprintf(("%s=" MANT_FMT "\n", "mul2", SOME_ARG(from, 0)));
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memset(temp, 0, sizeof temp);
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for (i = 0; i < MANT_LIMBS; i++) {
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for (j = 0; j < MANT_LIMBS; j++) {
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fp_2limb n;
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n = (fp_2limb) to[i] * (fp_2limb) from[j];
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temp[i + j] += n >> LIMB_BITS;
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temp[i + j + 1] += (fp_limb)n;
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}
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}
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for (i = MANT_LIMBS * 2; --i;) {
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temp[i - 1] += temp[i] >> LIMB_BITS;
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temp[i] &= LIMB_MASK;
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}
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dprintf(("%s=" MANT_FMT "_" MANT_FMT "\n", "temp", SOME_ARG(temp, 0),
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SOME_ARG(temp, MANT_LIMBS)));
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if (temp[0] & LIMB_TOP_BIT) {
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for (i = 0; i < MANT_LIMBS; i++) {
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to[i] = temp[i] & LIMB_MASK;
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}
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dprintf(("%s=" MANT_FMT " (%i)\n", "prod", SOME_ARG(to, 0), 0));
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return 0;
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} else {
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for (i = 0; i < MANT_LIMBS; i++) {
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to[i] = (temp[i] << 1) + !!(temp[i + 1] & LIMB_TOP_BIT);
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}
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dprintf(("%s=" MANT_FMT " (%i)\n", "prod", SOME_ARG(to, 0), -1));
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return -1;
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}
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}
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/*
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* ---------------------------------------------------------------------------
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* read an exponent; returns INT32_MAX on error
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* ---------------------------------------------------------------------------
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*/
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static int32_t read_exponent(const char *string, int32_t max)
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{
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int32_t i = 0;
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bool neg = false;
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if (*string == '+') {
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string++;
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} else if (*string == '-') {
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neg = true;
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string++;
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}
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while (*string) {
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if (*string >= '0' && *string <= '9') {
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i = (i * 10) + (*string - '0');
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/*
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* To ensure that underflows and overflows are
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* handled properly we must avoid wraparounds of
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* the signed integer value that is used to hold
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* the exponent. Therefore we cap the exponent at
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* +/-5000, which is slightly more/less than
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* what's required for normal and denormal numbers
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* in single, double, and extended precision, but
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* sufficient to avoid signed integer wraparound.
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*/
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if (i > max)
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i = max;
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} else if (*string == '_') {
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/* do nothing */
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} else {
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nasm_nonfatal("invalid character in floating-point constant %s: '%c'",
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"exponent", *string);
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return INT32_MAX;
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}
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string++;
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}
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return neg ? -i : i;
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}
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/*
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* ---------------------------------------------------------------------------
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* convert
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* ---------------------------------------------------------------------------
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*/
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static bool ieee_flconvert(const char *string, fp_limb *mant,
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int32_t * exponent)
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{
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char digits[MANT_DIGITS];
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char *p, *q, *r;
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fp_limb mult[MANT_LIMBS], bit;
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fp_limb *m;
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int32_t tenpwr, twopwr;
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int32_t extratwos;
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bool started, seendot, warned;
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warned = false;
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p = digits;
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tenpwr = 0;
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started = seendot = false;
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while (*string && *string != 'E' && *string != 'e') {
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if (*string == '.') {
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if (!seendot) {
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seendot = true;
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} else {
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nasm_nonfatal("too many periods in floating-point constant");
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return false;
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}
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} else if (*string >= '0' && *string <= '9') {
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if (*string == '0' && !started) {
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if (seendot) {
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tenpwr--;
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}
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} else {
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started = true;
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if (p < digits + sizeof(digits)) {
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*p++ = *string - '0';
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} else {
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if (!warned) {
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/*!
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*!float-toolong [on] too many digits in floating-point number
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*! warns about too many digits in floating-point numbers.
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*/
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nasm_warn(WARN_FLOAT_TOOLONG|ERR_PASS2,
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"floating-point constant significand contains "
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"more than %i digits", MANT_DIGITS);
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warned = true;
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}
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}
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if (!seendot) {
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tenpwr++;
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}
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}
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} else if (*string == '_') {
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/* do nothing */
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} else {
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nasm_nonfatalf(ERR_PASS2,
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"invalid character in floating-point constant %s: '%c'",
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"significand", *string);
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return false;
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}
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string++;
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}
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if (*string) {
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int32_t e;
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string++; /* eat the E */
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e = read_exponent(string, 5000);
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if (e == INT32_MAX)
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return false;
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tenpwr += e;
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}
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/*
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* At this point, the memory interval [digits,p) contains a
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* series of decimal digits zzzzzzz, such that our number X
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* satisfies X = 0.zzzzzzz * 10^tenpwr.
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*/
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q = digits;
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dprintf(("X = 0."));
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while (q < p) {
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dprintf(("%c", *q + '0'));
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q++;
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}
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dprintf((" * 10^%i\n", tenpwr));
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/*
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* Now convert [digits,p) to our internal representation.
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*/
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bit = LIMB_TOP_BIT;
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for (m = mant; m < mant + MANT_LIMBS; m++) {
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*m = 0;
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}
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m = mant;
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q = digits;
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started = false;
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twopwr = 0;
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while (m < mant + MANT_LIMBS) {
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fp_limb carry = 0;
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while (p > q && !p[-1]) {
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p--;
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}
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if (p <= q) {
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break;
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}
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for (r = p; r-- > q;) {
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int32_t i;
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i = 2 * *r + carry;
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if (i >= 10) {
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carry = 1;
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i -= 10;
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} else {
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carry = 0;
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}
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*r = i;
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}
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if (carry) {
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*m |= bit;
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started = true;
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}
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if (started) {
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if (bit == 1) {
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bit = LIMB_TOP_BIT;
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m++;
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} else {
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bit >>= 1;
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}
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} else {
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twopwr--;
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}
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}
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twopwr += tenpwr;
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/*
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* At this point, the 'mant' array contains the first frac-
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* tional places of a base-2^16 real number which when mul-
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* tiplied by 2^twopwr and 5^tenpwr gives X.
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*/
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dprintf(("X = " MANT_FMT " * 2^%i * 5^%i\n", MANT_ARG, twopwr,
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tenpwr));
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/*
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* Now multiply 'mant' by 5^tenpwr.
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*/
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if (tenpwr < 0) { /* mult = 5^-1 = 0.2 */
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for (m = mult; m < mult + MANT_LIMBS - 1; m++) {
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*m = LIMB_BYTE(0xcc);
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}
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mult[MANT_LIMBS - 1] = LIMB_BYTE(0xcc)+1;
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extratwos = -2;
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tenpwr = -tenpwr;
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/*
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* If tenpwr was 1000...000b, then it becomes 1000...000b. See
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* the "ANSI C" comment below for more details on that case.
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*
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* Because we already truncated tenpwr to +5000...-5000 inside
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* the exponent parsing code, this shouldn't happen though.
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*/
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} else if (tenpwr > 0) { /* mult = 5^+1 = 5.0 */
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mult[0] = (fp_limb)5 << (LIMB_BITS-3); /* 0xA000... */
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for (m = mult + 1; m < mult + MANT_LIMBS; m++) {
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*m = 0;
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}
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extratwos = 3;
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} else {
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extratwos = 0;
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}
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while (tenpwr) {
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dprintf(("loop=" MANT_FMT " * 2^%i * 5^%i (%i)\n", MANT_ARG,
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twopwr, tenpwr, extratwos));
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if (tenpwr & 1) {
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dprintf(("mant*mult\n"));
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twopwr += extratwos + float_multiply(mant, mult);
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}
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dprintf(("mult*mult\n"));
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extratwos = extratwos * 2 + float_multiply(mult, mult);
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tenpwr >>= 1;
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/*
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* In ANSI C, the result of right-shifting a signed integer is
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* considered implementation-specific. To ensure that the loop
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* terminates even if tenpwr was 1000...000b to begin with, we
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* manually clear the MSB, in case a 1 was shifted in.
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*
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* Because we already truncated tenpwr to +5000...-5000 inside
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* the exponent parsing code, this shouldn't matter; neverthe-
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* less it is the right thing to do here.
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*/
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tenpwr &= (uint32_t) - 1 >> 1;
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}
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/*
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* At this point, the 'mant' array contains the first frac-
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* tional places of a base-2^16 real number in [0.5,1) that
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* when multiplied by 2^twopwr gives X. Or it contains zero
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* of course. We are done.
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*/
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*exponent = twopwr;
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return true;
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}
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/*
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* ---------------------------------------------------------------------------
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* operations of specific bits
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* ---------------------------------------------------------------------------
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*/
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/* Set a bit, using *bigendian* bit numbering (0 = MSB) */
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static void set_bit(fp_limb *mant, size_t bit)
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{
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mant[bit/LIMB_BITS] |= (fp_limb)1 << (~bit & (LIMB_BITS-1));
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}
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/* Test a single bit */
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static int test_bit(const fp_limb *mant, size_t bit)
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{
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return (mant[bit/LIMB_BITS] >> (~bit & (LIMB_BITS-1))) & 1;
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}
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/* Report if the mantissa value is all zero */
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static bool is_zero(const fp_limb *mant)
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{
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int i;
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for (i = 0; i < MANT_LIMBS; i++)
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if (mant[i])
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return false;
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return true;
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}
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/*
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* ---------------------------------------------------------------------------
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* round a mantissa off after i words
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* ---------------------------------------------------------------------------
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*/
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#define ROUND_COLLECT_BITS \
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do { \
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m = mant[i] & (2*bit-1); \
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for (j = i+1; j < MANT_LIMBS; j++) \
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m = m | mant[j]; \
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} while (0)
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#define ROUND_ABS_DOWN \
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do { \
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mant[i] &= ~(bit-1); \
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for (j = i+1; j < MANT_LIMBS; j++) \
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mant[j] = 0; \
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return false; \
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} while (0)
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#define ROUND_ABS_UP \
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do { \
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mant[i] = (mant[i] & ~(bit-1)) + bit; \
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for (j = i+1; j < MANT_LIMBS; j++) \
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mant[j] = 0; \
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while (i > 0 && !mant[i]) \
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++mant[--i]; \
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return !mant[0]; \
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} while (0)
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static bool ieee_round(bool minus, fp_limb *mant, int bits)
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{
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fp_limb m = 0;
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int32_t j;
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int i = bits / LIMB_BITS;
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int p = bits % LIMB_BITS;
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fp_limb bit = LIMB_TOP_BIT >> p;
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if (rc == FLOAT_RC_NEAR) {
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if (mant[i] & bit) {
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mant[i] &= ~bit;
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ROUND_COLLECT_BITS;
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mant[i] |= bit;
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if (m) {
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ROUND_ABS_UP;
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} else {
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if (test_bit(mant, bits-1)) {
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ROUND_ABS_UP;
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} else {
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ROUND_ABS_DOWN;
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}
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}
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} else {
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ROUND_ABS_DOWN;
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}
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} else if (rc == FLOAT_RC_ZERO ||
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rc == (minus ? FLOAT_RC_UP : FLOAT_RC_DOWN)) {
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ROUND_ABS_DOWN;
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} else {
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/* rc == (minus ? FLOAT_RC_DOWN : FLOAT_RC_UP) */
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/* Round toward +/- infinity */
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ROUND_COLLECT_BITS;
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if (m) {
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ROUND_ABS_UP;
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} else {
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ROUND_ABS_DOWN;
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}
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}
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return false;
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}
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/* Returns a value >= 16 if not a valid hex digit */
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static unsigned int hexval(char c)
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{
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unsigned int v = (unsigned char) c;
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if (v >= '0' && v <= '9')
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return v - '0';
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else
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return (v|0x20) - 'a' + 10;
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}
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/* Handle floating-point numbers with radix 2^bits and binary exponent */
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static bool ieee_flconvert_bin(const char *string, int bits,
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fp_limb *mant, int32_t *exponent)
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{
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static const int log2tbl[16] =
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{ -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3 };
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fp_limb mult[MANT_LIMBS + 1], *mp;
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int ms;
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int32_t twopwr;
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bool seendot, seendigit;
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unsigned char c;
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const int radix = 1 << bits;
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fp_limb v;
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twopwr = 0;
|
|
seendot = seendigit = false;
|
|
ms = 0;
|
|
mp = NULL;
|
|
|
|
memset(mult, 0, sizeof mult);
|
|
|
|
while ((c = *string++) != '\0') {
|
|
if (c == '.') {
|
|
if (!seendot)
|
|
seendot = true;
|
|
else {
|
|
nasm_nonfatal("too many periods in floating-point constant");
|
|
return false;
|
|
}
|
|
} else if ((v = hexval(c)) < (unsigned int)radix) {
|
|
if (!seendigit && v) {
|
|
int l = log2tbl[v];
|
|
|
|
seendigit = true;
|
|
mp = mult;
|
|
ms = (LIMB_BITS-1)-l;
|
|
|
|
twopwr += l+1-bits;
|
|
}
|
|
|
|
if (seendigit) {
|
|
if (ms < 0) {
|
|
/* Cast to fp_2limb as ms == -LIMB_BITS is possible. */
|
|
*mp |= (fp_2limb)v >> -ms;
|
|
mp++;
|
|
if (mp > &mult[MANT_LIMBS])
|
|
mp = &mult[MANT_LIMBS]; /* Guard slot */
|
|
ms += LIMB_BITS;
|
|
}
|
|
*mp |= v << ms;
|
|
ms -= bits;
|
|
|
|
if (!seendot)
|
|
twopwr += bits;
|
|
} else {
|
|
if (seendot)
|
|
twopwr -= bits;
|
|
}
|
|
} else if (c == 'p' || c == 'P') {
|
|
int32_t e;
|
|
e = read_exponent(string, 20000);
|
|
if (e == INT32_MAX)
|
|
return false;
|
|
twopwr += e;
|
|
break;
|
|
} else if (c == '_') {
|
|
/* ignore */
|
|
} else {
|
|
nasm_nonfatal("floating-point constant: `%c' is invalid character", c);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
if (!seendigit) {
|
|
memset(mant, 0, MANT_LIMBS*sizeof(fp_limb)); /* Zero */
|
|
*exponent = 0;
|
|
} else {
|
|
memcpy(mant, mult, MANT_LIMBS*sizeof(fp_limb));
|
|
*exponent = twopwr;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Shift a mantissa to the right by i bits.
|
|
*/
|
|
static void ieee_shr(fp_limb *mant, int i)
|
|
{
|
|
fp_limb n, m;
|
|
int j = 0;
|
|
int sr, sl, offs;
|
|
|
|
sr = i % LIMB_BITS; sl = LIMB_BITS-sr;
|
|
offs = i/LIMB_BITS;
|
|
|
|
if (sr == 0) {
|
|
if (offs)
|
|
for (j = MANT_LIMBS-1; j >= offs; j--)
|
|
mant[j] = mant[j-offs];
|
|
} else if (MANT_LIMBS-1-offs < 0) {
|
|
j = MANT_LIMBS-1;
|
|
} else {
|
|
n = mant[MANT_LIMBS-1-offs] >> sr;
|
|
for (j = MANT_LIMBS-1; j > offs; j--) {
|
|
m = mant[j-offs-1];
|
|
mant[j] = (m << sl) | n;
|
|
n = m >> sr;
|
|
}
|
|
mant[j--] = n;
|
|
}
|
|
while (j >= 0)
|
|
mant[j--] = 0;
|
|
}
|
|
|
|
/* Produce standard IEEE formats, with implicit or explicit integer
|
|
bit; this makes the following assumptions:
|
|
|
|
- the sign bit is the MSB, followed by the exponent,
|
|
followed by the integer bit if present.
|
|
- the sign bit plus exponent fit in 16 bits.
|
|
- the exponent bias is 2^(n-1)-1 for an n-bit exponent */
|
|
|
|
/*
|
|
* The 16- and 128-bit formats are expected to be in IEEE 754r.
|
|
* AMD SSE5 uses the 16-bit format.
|
|
*
|
|
* The 32- and 64-bit formats are the original IEEE 754 formats.
|
|
*
|
|
* The 80-bit format is x87-specific, but widely used.
|
|
*
|
|
* The 8-bit format appears to be the consensus 8-bit floating-point
|
|
* format. It is apparently used in graphics applications.
|
|
*
|
|
* The b16 format is a 16-bit format with smaller mantissa and larger
|
|
* exponent field. It is effectively a truncated version of the standard
|
|
* IEEE 32-bit (single) format, but is explicitly supported here in
|
|
* order to support proper rounding.
|
|
*
|
|
* This array must correspond to enum floatize in include/nasm.h.
|
|
* Note that there are some formats which have more than one enum;
|
|
* both need to be listed here with the appropriate offset into the
|
|
* floating-point byte array (use for the floatize operators.)
|
|
*
|
|
* FLOAT_ERR is a value that both represents "invalid format" and the
|
|
* size of this array.
|
|
*/
|
|
const struct ieee_format fp_formats[FLOAT_ERR] = {
|
|
{ 1, 3, 0, 4, 0 }, /* FLOAT_8 */
|
|
{ 2, 10, 0, 5, 0 }, /* FLOAT_16 */
|
|
{ 2, 7, 0, 8, 0 }, /* FLOAT_B16 */
|
|
{ 4, 23, 0, 8, 0 }, /* FLOAT_32 */
|
|
{ 8, 52, 0, 11, 0 }, /* FLOAT_64 */
|
|
{ 10, 63, 1, 15, 0 }, /* FLOAT_80M */
|
|
{ 10, 63, 1, 15, 8 }, /* FLOAT_80E */
|
|
{ 16, 112, 0, 15, 0 }, /* FLOAT_128L */
|
|
{ 16, 112, 0, 15, 8 } /* FLOAT_128H */
|
|
};
|
|
|
|
/* Types of values we can generate */
|
|
enum floats {
|
|
FL_ZERO,
|
|
FL_DENORMAL,
|
|
FL_NORMAL,
|
|
FL_INFINITY,
|
|
FL_QNAN,
|
|
FL_SNAN
|
|
};
|
|
|
|
static int to_packed_bcd(const char *str, const char *p,
|
|
int s, uint8_t *result,
|
|
const struct ieee_format *fmt)
|
|
{
|
|
int n = 0;
|
|
char c;
|
|
int tv = -1;
|
|
|
|
if (fmt->bytes != 10) {
|
|
nasm_nonfatal("packed BCD requires an 80-bit format");
|
|
return 0;
|
|
}
|
|
|
|
while (p >= str) {
|
|
c = *p--;
|
|
if (c >= '0' && c <= '9') {
|
|
if (tv < 0) {
|
|
if (n == 9)
|
|
nasm_warn(WARN_OTHER|ERR_PASS2, "packed BCD truncated to 18 digits");
|
|
tv = c-'0';
|
|
} else {
|
|
if (n < 9)
|
|
*result++ = tv + ((c-'0') << 4);
|
|
n++;
|
|
tv = -1;
|
|
}
|
|
} else if (c == '_') {
|
|
/* do nothing */
|
|
} else {
|
|
nasm_nonfatal("invalid character `%c' in packed BCD constant", c);
|
|
return 0;
|
|
}
|
|
}
|
|
if (tv >= 0) {
|
|
if (n < 9)
|
|
*result++ = tv;
|
|
n++;
|
|
}
|
|
while (n < 9) {
|
|
*result++ = 0;
|
|
n++;
|
|
}
|
|
*result = (s < 0) ? 0x80 : 0;
|
|
|
|
return 1; /* success */
|
|
}
|
|
|
|
int float_const(const char *str, int s, uint8_t *result, enum floatize ffmt)
|
|
{
|
|
const struct ieee_format *fmt = &fp_formats[ffmt];
|
|
fp_limb mant[MANT_LIMBS];
|
|
int32_t exponent = 0;
|
|
const int32_t expmax = 1 << (fmt->exponent - 1);
|
|
fp_limb one_mask = LIMB_TOP_BIT >>
|
|
((fmt->exponent+fmt->explicit) % LIMB_BITS);
|
|
const int one_pos = (fmt->exponent+fmt->explicit)/LIMB_BITS;
|
|
int i;
|
|
int shift;
|
|
enum floats type;
|
|
bool ok;
|
|
const bool minus = s < 0;
|
|
const int bits = fmt->bytes * 8;
|
|
const char *strend;
|
|
|
|
nasm_assert(str[0]);
|
|
|
|
strend = strchr(str, '\0');
|
|
if (strend[-1] == 'P' || strend[-1] == 'p')
|
|
return to_packed_bcd(str, strend-2, s, result, fmt);
|
|
|
|
if (str[0] == '_') {
|
|
/* Special tokens */
|
|
|
|
switch (str[3]) {
|
|
case 'n': /* __?nan?__ */
|
|
case 'N':
|
|
case 'q': /* __?qnan?__ */
|
|
case 'Q':
|
|
type = FL_QNAN;
|
|
break;
|
|
case 's': /* __?snan?__ */
|
|
case 'S':
|
|
type = FL_SNAN;
|
|
break;
|
|
case 'i': /* __?infinity?__ */
|
|
case 'I':
|
|
type = FL_INFINITY;
|
|
break;
|
|
default:
|
|
nasm_nonfatal("internal error: unknown FP constant token `%s'", str);
|
|
type = FL_QNAN;
|
|
break;
|
|
}
|
|
} else {
|
|
if (str[0] == '0') {
|
|
switch (str[1]) {
|
|
case 'x': case 'X':
|
|
case 'h': case 'H':
|
|
ok = ieee_flconvert_bin(str+2, 4, mant, &exponent);
|
|
break;
|
|
case 'o': case 'O':
|
|
case 'q': case 'Q':
|
|
ok = ieee_flconvert_bin(str+2, 3, mant, &exponent);
|
|
break;
|
|
case 'b': case 'B':
|
|
case 'y': case 'Y':
|
|
ok = ieee_flconvert_bin(str+2, 1, mant, &exponent);
|
|
break;
|
|
case 'd': case 'D':
|
|
case 't': case 'T':
|
|
ok = ieee_flconvert(str+2, mant, &exponent);
|
|
break;
|
|
case 'p': case 'P':
|
|
return to_packed_bcd(str+2, strend-1, s, result, fmt);
|
|
default:
|
|
/* Leading zero was just a zero? */
|
|
ok = ieee_flconvert(str, mant, &exponent);
|
|
break;
|
|
}
|
|
} else if (str[0] == '$') {
|
|
ok = ieee_flconvert_bin(str+1, 4, mant, &exponent);
|
|
} else {
|
|
ok = ieee_flconvert(str, mant, &exponent);
|
|
}
|
|
|
|
if (!ok) {
|
|
type = FL_QNAN;
|
|
} else if (mant[0] & LIMB_TOP_BIT) {
|
|
/*
|
|
* Non-zero.
|
|
*/
|
|
exponent--;
|
|
if (exponent >= 2 - expmax && exponent <= expmax) {
|
|
type = FL_NORMAL;
|
|
} else if (exponent > 0) {
|
|
nasm_warn(WARN_FLOAT_OVERFLOW|ERR_PASS2,
|
|
"overflow in floating-point constant");
|
|
type = FL_INFINITY;
|
|
} else {
|
|
/* underflow or denormal; the denormal code handles
|
|
actual underflow. */
|
|
type = FL_DENORMAL;
|
|
}
|
|
} else {
|
|
/* Zero */
|
|
type = FL_ZERO;
|
|
}
|
|
}
|
|
|
|
switch (type) {
|
|
case FL_ZERO:
|
|
zero:
|
|
memset(mant, 0, sizeof mant);
|
|
break;
|
|
|
|
case FL_DENORMAL:
|
|
{
|
|
shift = -(exponent + expmax - 2 - fmt->exponent)
|
|
+ fmt->explicit;
|
|
ieee_shr(mant, shift);
|
|
ieee_round(minus, mant, bits);
|
|
if (mant[one_pos] & one_mask) {
|
|
/* One's position is set, we rounded up into normal range */
|
|
exponent = 1;
|
|
if (!fmt->explicit)
|
|
mant[one_pos] &= ~one_mask; /* remove explicit one */
|
|
mant[0] |= exponent << (LIMB_BITS-1 - fmt->exponent);
|
|
} else {
|
|
if (daz || is_zero(mant)) {
|
|
/*!
|
|
*!float-underflow [off] floating point underflow
|
|
*! warns about floating point underflow (a nonzero
|
|
*! constant rounded to zero.)
|
|
*/
|
|
nasm_warn(WARN_FLOAT_UNDERFLOW|ERR_PASS2,
|
|
"underflow in floating-point constant");
|
|
goto zero;
|
|
} else {
|
|
/*!
|
|
*!float-denorm [off] floating point denormal
|
|
*! warns about denormal floating point constants.
|
|
*/
|
|
nasm_warn(WARN_FLOAT_DENORM|ERR_PASS2,
|
|
"denormal floating-point constant");
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
case FL_NORMAL:
|
|
exponent += expmax - 1;
|
|
ieee_shr(mant, fmt->exponent+fmt->explicit);
|
|
ieee_round(minus, mant, bits);
|
|
/* did we scale up by one? */
|
|
if (test_bit(mant, fmt->exponent+fmt->explicit-1)) {
|
|
ieee_shr(mant, 1);
|
|
exponent++;
|
|
if (exponent >= (expmax << 1)-1) {
|
|
/*!
|
|
*!float-overflow [on] floating point overflow
|
|
*! warns about floating point underflow.
|
|
*/
|
|
nasm_warn(WARN_FLOAT_OVERFLOW|ERR_PASS2,
|
|
"overflow in floating-point constant");
|
|
type = FL_INFINITY;
|
|
goto overflow;
|
|
}
|
|
}
|
|
|
|
if (!fmt->explicit)
|
|
mant[one_pos] &= ~one_mask; /* remove explicit one */
|
|
mant[0] |= exponent << (LIMB_BITS-1 - fmt->exponent);
|
|
break;
|
|
|
|
case FL_INFINITY:
|
|
case FL_QNAN:
|
|
case FL_SNAN:
|
|
overflow:
|
|
memset(mant, 0, sizeof mant);
|
|
mant[0] = (((fp_limb)1 << fmt->exponent)-1)
|
|
<< (LIMB_BITS-1 - fmt->exponent);
|
|
if (fmt->explicit)
|
|
mant[one_pos] |= one_mask;
|
|
if (type == FL_QNAN)
|
|
set_bit(mant, fmt->exponent+fmt->explicit+1);
|
|
else if (type == FL_SNAN)
|
|
set_bit(mant, fmt->exponent+fmt->explicit+fmt->mantissa);
|
|
break;
|
|
}
|
|
|
|
mant[0] |= minus ? LIMB_TOP_BIT : 0;
|
|
|
|
for (i = fmt->bytes - 1; i >= 0; i--)
|
|
*result++ = mant[i/LIMB_BYTES] >> (((LIMB_BYTES-1)-(i%LIMB_BYTES))*8);
|
|
|
|
return 1; /* success */
|
|
}
|
|
|
|
/*
|
|
* Get the default floating point format for this specific field size.
|
|
* Used for the Dx pseudoops.
|
|
*/
|
|
enum floatize float_deffmt(int bytes)
|
|
{
|
|
enum floatize type;
|
|
|
|
for (type = 0; type < FLOAT_ERR; type++) {
|
|
if (fp_formats[type].bytes == bytes)
|
|
break;
|
|
}
|
|
|
|
return type; /* FLOAT_ERR if invalid */
|
|
}
|
|
|
|
/* Set floating-point options */
|
|
int float_option(const char *option)
|
|
{
|
|
if (!nasm_stricmp(option, "daz")) {
|
|
daz = true;
|
|
return 0;
|
|
} else if (!nasm_stricmp(option, "nodaz")) {
|
|
daz = false;
|
|
return 0;
|
|
} else if (!nasm_stricmp(option, "near")) {
|
|
rc = FLOAT_RC_NEAR;
|
|
return 0;
|
|
} else if (!nasm_stricmp(option, "down")) {
|
|
rc = FLOAT_RC_DOWN;
|
|
return 0;
|
|
} else if (!nasm_stricmp(option, "up")) {
|
|
rc = FLOAT_RC_UP;
|
|
return 0;
|
|
} else if (!nasm_stricmp(option, "zero")) {
|
|
rc = FLOAT_RC_ZERO;
|
|
return 0;
|
|
} else if (!nasm_stricmp(option, "default")) {
|
|
rc = FLOAT_RC_NEAR;
|
|
daz = false;
|
|
return 0;
|
|
} else {
|
|
return -1; /* Unknown option */
|
|
}
|
|
}
|