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/* See LICENSE file for copyright and license details. */
#include "internals.h"
#include <stdio.h>
#define num libzahl_tmp_str_num
#define rem libzahl_tmp_str_rem
/* All 19 you see here is derived from that 10¹⁹ is the largest
* power of than < 2⁶⁴, and 64 is the number of bits in
* zahl_char_t. If zahl_char_t is chanced, the value 19, and
* the cast to unsigned long long must be changed accordingly. */
char *
zstr(z_t a, char *b)
{
char buf[19 + 1];
size_t n, len;
char overridden = 0;
int neg;
if (zzero(a)) {
if (!b) {
b = malloc(2);
if (!b)
FAILURE(errno);
}
b[0] = '0';
b[1] = 0;
return b;
}
n = zstr_length(a, 10);
if (!b) {
b = malloc(n + 1);
if (!b)
FAILURE(errno);
}
neg = zsignum(a) < 0;
zabs(num, a);
b[0] = '-';
b += neg;
n -= neg;
n = n > 19 ? (n - 19) : 0;
for (;;) {
zdivmod(num, rem, num, libzahl_const_1e19);
if (!zzero(num)) {
sprintf(b + n, "%019llu", zzero(rem) ? 0ULL : (unsigned long long)(rem->chars[0]));
b[n + 19] = overridden;
overridden = b[n];
n = n > 19 ? (n - 19) : 0;
} else {
len = (size_t)sprintf(buf, "%llu", (unsigned long long)(rem->chars[0]));
if (overridden)
buf[len] = b[n + len];
memcpy(b + n, buf, len + 1);
break;
}
}
return b - neg;
}
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