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Avoid using alloca in fixnum

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This commit is contained in:
Ekaitz Zarraga 2020-05-23 15:33:29 +02:00
parent a2312503c4
commit 3745c16c8c
1 changed files with 22 additions and 3 deletions
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25
lib/chibi/json.c
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@ -327,10 +327,29 @@ sexp unparse_json_fixnum(sexp ctx, sexp self, const sexp obj) {
sexp_gc_var2(res, tmp);
sexp_gc_preserve2(ctx, res, tmp);
res = SEXP_NULL;
int sign = 1;
long num = sexp_unbox_fixnum(obj);
char* buff = alloca( num==0 ? 2 : (log10(abs(num))+3) );
sprintf(buff, "%ld", num);
res = sexp_c_string(ctx, buff, -1);
char digit;
if (num == 0) {
res = sexp_c_string(ctx, "0", -1);
} else {
if (num < 0) {
sign = -1;
num = labs(num);
}
while (num > 0) {
digit = '0' + num%10;
num /= 10;
tmp = sexp_c_string(ctx, &digit, 1);
res = sexp_cons(ctx, tmp, res);
}
if (sign==-1) {
tmp = sexp_c_string(ctx, "-", -1);
res = sexp_cons(ctx, tmp, res);
}
res = sexp_string_concatenate(ctx, res, SEXP_FALSE);
}
sexp_gc_release2(ctx);
return res;
}