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/* See LICENSE file for copyright and license details. */
#include "internals.h"
void
zadd_unsigned(z_t a, z_t b, z_t c)
{
size_t i, size, n;
uint32_t carry[] = {0, 0};
zahl_char_t *addend;
if (EXPECT(zzero(b), 0)) {
zabs(a, c);
return;
} else if (EXPECT(zzero(c), 0)) {
zabs(a, b);
return;
}
size = MAX(b->used, c->used);
n = b->used + c->used - size;
ENSURE_SIZE(a, size + 1);
a->chars[size] = 0;
if (a == b) {
if (a->used < c->used) {
n = c->used;
zmemset(a->chars + a->used, 0, n - a->used);
}
addend = c->chars;
} else if (EXPECT(a == c, 0)) {
if (a->used < b->used) {
n = b->used;
zmemset(a->chars + a->used, 0, n - a->used);
}
addend = b->chars;
} else if (b->used > c->used) {
zmemcpy(a->chars, b->chars, b->used);
a->used = b->used;
addend = c->chars;
} else {
zmemcpy(a->chars, c->chars, c->used);
a->used = c->used;
addend = b->chars;
}
for (i = 0; i < n; i++) {
if (carry[i & 1])
carry[~i & 1] = (ZAHL_CHAR_MAX - a->chars[i] <= addend[i]);
else
carry[~i & 1] = (ZAHL_CHAR_MAX - a->chars[i] < addend[i]);
a->chars[i] += addend[i] + carry[i & 1];
}
while (carry[i & 1]) {
carry[~i & 1] = a->chars[i] == ZAHL_CHAR_MAX;
a->chars[i++] += 1;
}
if (a->used < i)
a->used = i;
SET_SIGNUM(a, 1);
}
void
zadd(z_t a, z_t b, z_t c)
{
if (EXPECT(zzero(b), 0)) {
SET(a, c);
} else if (EXPECT(zzero(c), 0)) {
SET(a, b);
} else if (EXPECT(b == c, 0)) {
zlsh(a, b, 1);
} else if (EXPECT((zsignum(b) | zsignum(c)) < 0, 0)) {
if (zsignum(b) < 0) {
if (zsignum(c) < 0) {
zadd_unsigned(a, b, c);
SET_SIGNUM(a, -zsignum(a));
} else {
zsub_unsigned(a, c, b);
}
} else {
zsub_unsigned(a, b, c);
}
} else {
zadd_unsigned(a, b, c);
}
}
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