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preproc: add %num() to format a number in an arbitrary base

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Add the %num() preprocessor function, which returns a quoted string
with a number formatted in any base between 2 and 64 (using bash
encoding with '@' for 62 and '_' for 63.)

It can specify a fixed number of digits with or without truncation.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2022-11-15 16:55:37 -08:00
parent 5a25ad12b2
commit 1d1ba9c7d7
1 changed files with 82 additions and 0 deletions
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82
asm/preproc.c
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@ -7143,6 +7143,80 @@ stdmac_count(const SMacro *s, Token **params, int nparams)
return make_tok_num(NULL, nparams);
}
/* %num() */
static Token *
stdmac_num(const SMacro *s, Token **params, int nparams)
{
static const char num_digits[] =
"0123456789"
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"@_"; /* Compatible with bash */
int64_t parm[3];
uint64_t n;
int64_t dparm, bparm;
int i, nd;
unsigned int base;
char numstr[256];
char * const endstr = numstr + sizeof numstr - 1;
const int maxlen = sizeof numstr - 3;
const int maxbase = sizeof num_digits - 1;
char *p;
bool moredigits;
if (nparams < 1 || nparams > (int)ARRAY_SIZE(parm)) {
nasm_nonfatal("invalid number of parameters to %s()", s->name);
return NULL;
}
parm[1] = 10; /* Default base */
parm[2] = -1; /* Default digits */
for (i = 0; i < nparams; i++) {
bool err;
parm[i] = get_tok_num(params[i], &err);
if (err)
return NULL;
}
n = parm[0];
bparm = parm[1];
dparm = parm[2];
if (bparm < 2 || bparm > maxbase) {
nasm_nonfatal("invalid base %"PRId64" given to %s()",
bparm, s->name);
return NULL;
}
base = bparm;
if (dparm < -maxlen || dparm > maxlen) {
nasm_nonfatal("digit count %"PRId64" specified to %s() too large",
dparm, s->name);
moredigits = true;
nd = 1;
} else if (dparm <= 0) {
moredigits = true;
nd = -dparm;
} else {
moredigits = false;
nd = dparm;
}
p = endstr;
*p = '\0';
*--p = '\'';
while (nd-- > 0 || (moredigits && n)) {
*--p = num_digits[n % base];
n /= base;
}
*--p = '\'';
return new_Token(NULL, TOKEN_STR, p, endstr - p);
}
/* Add magic standard macros */
struct magic_macros {
const char *name;
@ -7151,6 +7225,13 @@ struct magic_macros {
enum sparmflags flags;
ExpandSMacro func;
};
struct num_macros {
const char name[6];
uint8_t base;
char prefix;
};
static void pp_add_magic_stdmac(void)
{
static const struct magic_macros magic_macros[] = {
@ -7160,6 +7241,7 @@ static void pp_add_magic_stdmac(void)
{ "__?PTR?__", true, 0, 0, stdmac_ptr },
{ "%count", false, 1, SPARM_VARADIC, stdmac_count },
{ "%eval", false, 1, SPARM_EVAL|SPARM_VARADIC, stdmac_join },
{ "%num", false, 1, SPARM_EVAL|SPARM_VARADIC, stdmac_num },
{ "%str", false, 1, SPARM_GREEDY|SPARM_STR, stdmac_join },
{ "%strcat", false, 1, SPARM_GREEDY, stdmac_strcat },
{ "%strlen", false, 1, 0, stdmac_strlen },