Files
gw-basic-2026/include/analysis.h
Eremey Valetov 89fe0fb0b3 Compiler: $EXTERN pragma for calling C functions from BASIC (Level 2 FFI) (#1)
Add a '$EXTERN NAME(ARGTYPES) AS RET pragma so compiled BASIC can call C
functions directly, the natural follow-up to Level 1 (--emit-obj /
--main-name). The pragma is an apostrophe comment, so the interpreter
ignores it while the compiler registers it.

Map INTEGER/SINGLE/DOUBLE/STRING to int16_t/float/double/const char* at the
boundary: a string argument crosses as a temporary C copy that is freed
after the call, and a string return is copied into the pool. The call name
is matched case-insensitively but emitted as the C symbol with the case
written in the pragma. Names are recognized before parse_var() truncates
identifiers to two significant characters, so multi-character C function
names work.

A string return that aliases a char* argument is copied before the argument
temporaries are freed, which avoids a use-after-free. Over-supplied
arguments are consumed without desyncing the token stream and warn on arity
mismatch.

Docs: getting-started.md "Foreign Functions from BASIC". Test:
tests/run_ffi_test.sh, wired into CI. 63/63 compiler, 72/72 interpreter,
68/68 compat still pass.

Also refile the roadmap "Next Up" backlog as git-bug issues and prune
docs/roadmap.md to point at git-bug as the source of truth for planned work.

Co-authored-by: Eremey Valetov <evvaletov@users.noreply.github.com>
2026-06-13 15:06:23 +03:00

83 lines
2.3 KiB
C

#ifndef ANALYSIS_H
#define ANALYSIS_H
#include "types.h"
#include <stdbool.h>
#include <stdint.h>
#define MAX_LINES 8192
#define MAX_VARS 1024
#define MAX_GOTOS 1024
#define MAX_DATA 4096
#define MAX_GOSUB_RET 1024
#define MAX_EXTERNS 64
#define MAX_EXTERN_ARGS 8
#define EXTERN_NAME_MAX 32
typedef struct {
uint16_t line_num;
bool is_target; /* referenced by GOTO/GOSUB/etc. */
bool has_data; /* contains DATA statement */
int data_start; /* index into data pool */
} line_info_t;
/* A C function declared via the '$EXTERN NAME(ARGS) AS RET pragma.
* name is stored case-preserving (emitted as the C symbol); matching
* against BASIC call sites is case-insensitive. */
typedef struct {
char name[EXTERN_NAME_MAX];
gw_valtype_t ret_type;
gw_valtype_t arg_types[MAX_EXTERN_ARGS];
int argc;
} extern_func_t;
typedef struct {
char name[2];
gw_valtype_t type;
uint16_t first_assign_line; /* 0 = never assigned */
uint16_t first_use_line; /* 0 = never used */
} var_info_t;
typedef struct {
line_info_t lines[MAX_LINES];
int line_count;
var_info_t vars[MAX_VARS];
int var_count;
uint16_t goto_targets[MAX_GOTOS];
int goto_count;
char *data_pool[MAX_DATA]; /* collected DATA literals */
int data_count;
int data_line_map[MAX_LINES][2]; /* [line_num, data_start_index] */
int data_line_count;
gw_valtype_t def_type[26]; /* from DEFINT/DEFSNG/DEFDBL/DEFSTR */
extern_func_t externs[MAX_EXTERNS]; /* '$EXTERN FFI declarations */
int extern_count;
} analysis_t;
/* Run analysis pass over the loaded program */
void analysis_run(analysis_t *a);
/* Find a variable in the census, return index or -1 */
int analysis_find_var(analysis_t *a, const char name[2], gw_valtype_t type);
/* Add a variable to the census if not already present */
int analysis_add_var(analysis_t *a, const char name[2], gw_valtype_t type);
/* Check if a line number is a jump target */
bool analysis_is_target(analysis_t *a, uint16_t line_num);
/* Find a declared extern function by name (case-insensitive), or NULL */
const extern_func_t *analysis_find_extern(analysis_t *a, const char *name);
/* Emit static analysis warnings to stderr */
void analysis_warnings(analysis_t *a);
#endif