diff options
Diffstat (limited to 'doc/nasmdoc.src')
| -rw-r--r-- | doc/nasmdoc.src | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/doc/nasmdoc.src b/doc/nasmdoc.src index 0f802663..2828c7f3 100644 --- a/doc/nasmdoc.src +++ b/doc/nasmdoc.src @@ -1411,6 +1411,19 @@ then no other definition of \c{foo} will be accepted: a macro with no parameters prohibits the definition of the same name as a macro \e{with} parameters, and vice versa. +This doesn't prevent single-line macros being \e{redefined}: you can +perfectly well define a macro with + +\c %define foo bar + +and then re-define it later in the same source file with + +\c %define foo baz + +Then everywhere the macro \c{foo} is invoked, it will be expanded +according to the most recent definition. This is particularly useful +when defining single-line macros with \c{%assign} (see \k{assign}). + You can \i{pre-define} single-line macros using the `-d' option on the NASM command line: see \k{opt-d}. @@ -1426,6 +1439,13 @@ parameters and have a numeric value. This value can be specified in the form of an expression, and it will be evaluated once, when the \c{%assign} directive is processed. +Like \c{%define}, macros defined using \c{%assign} can be re-defined +later, so you can do things like + +\c %assign i i+1 + +to increment the numeric value of a macro. + \c{%assign} is useful for controlling the termination of \c{%rep} preprocessor loops: see \k{rep} for an example of this. Another use for \c{%assign} is given in \k{16c} and \k{32c}. @@ -1480,7 +1500,7 @@ things like \c silly 'ab', string_ab ; string_ab: db 'ab' \c silly {13,10}, crlf ; crlf: db 13,10 -\S{mlmacover} \I{Overloading Multi-Line Macros} +\S{mlmacover} \i{Overloading Multi-Line Macros} As with single-line macros, multi-line macros can be overloaded by defining the same macro name several times with different numbers of |