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doc: editorial cleanups

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Clean up the language of a few sections, add a few examples, and
better document %pragma limit.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin (Intel)
2020-06-27 16:40:52 -07:00
parent f0dc62c6a6
commit fa7732e092
1 changed files with 37 additions and 15 deletions
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doc/nasmdoc.src
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@@ -923,10 +923,13 @@ shown in \k{opt-pragma} is the same as running this:
\S{opt-limit} The \i\c{--limit-X} Option
This option allows user to setup various maximum values for these:
This option allows user to setup various maximum values after which
NASM will terminate with a fatal error rather than consume arbitrary
amount of compute time. Each limit can be set to a positive number or
\c{unlimited}.
\b\c{--limit-passes}: Number of maximum allowed passes. Default is
effectively unlimited.
\c{unlimited}.
\b\c{--limit-stalled-passes}: Maximum number of allowed unfinished
passes. Default is 1000.
@@ -946,13 +949,18 @@ under \c{%rep}. Default is 1000000.
\b\c{--limit-eval}: This number sets the boundary condition of allowed
expression length. Default is 8192 on most systems.
\b\c{--limit-lines}: Total number of source lines as allowed to be
\b\c{--limit-lines}: Total number of source lines allowed to be
processed. Default is 2000000000.
In example, running this limits the maximum line count to be 1000.
For example, set the maximum line count to 1000:
\c nasm --limit-lines 1000
Limits can also be set via the directive \c{%pragma limit}, for
example:
\c %pragma limit lines 1000
\S{opt-keep-all} The \i\c{--keep-all} Option
@@ -2492,23 +2500,37 @@ includes backwards compatibility aliases defined by NASM itself.
To disable aliases without undefining them, use the \c{%aliases off}
directive.
To check whether an alias is defined, use \c{%ifdefalias}.
To check whether an alias is defined, regardless of the existence of
the aliased macro, use \c{%ifdefalias}.
This
For example:
\c %defalias OLD NEW
\c ; OLD and NEW both undefined
\c %define NEW 123
\c ; OLD and NEW both 123
\c %undef OLD
\c ; OLD and NEW both undefined
\c %define OLD 456
\c ; OLD and NEW both 456
\c %undefalias OLD
\c ; OLD undefined, NEW defined to 456
\S{cond-comma} \i{Conditional Comma Operator}: \i\c{%,}
As of version 2.15, NASM has conditional comma operator \c{%,} that expands to a
comma unless followed by a null expansion, which allows suppressing the comma before an
empty argument. For example, all the expressions below are valid:
As of version 2.15, NASM has a conditional comma operator \c{%,} that
expands to a comma \e{unless} followed by a null expansion, which
allows suppressing the comma before an empty argument. This is
especially useful with greedy single-line macros.
For example, all the expressions below are valid:
\c %define greedy(a,b,c+) a + 66 %, b * 3 %, c
\c
\c db greedy(1,2)
\c db greedy(1,2,3)
\c db greedy(1,2,3,4)
\c db greedy(1,2,3,4,5)
\c db greedy(1,2) ; db 1 + 66, 2 * 3
\c db greedy(1,2,3) ; db 1 + 66, 2 * 3, 3
\c db greedy(1,2,3,4) ; db 1 + 66, 2 * 3, 3, 4
\c db greedy(1,2,3,4,5) ; db 1 + 66, 2 * 3, 3, 4, 5
\H{strlen} \i{String Manipulation in Macros}
@@ -3402,8 +3424,8 @@ infinite loop in the preprocessor, which (on multitasking or
multi-user systems) would typically cause all the system memory to
be gradually used up and other applications to start crashing.
Note a maximum repeat count is limited by 62 bit number, though it
is hardly possible that you ever need anything bigger.
Note the maximum repeat count is limited to the value specified by the
\c{--limit-rep} option or \c{%pragma limit rep}, see \k{opt-limit}.
\H{files} Source Files and Dependencies