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/* See LICENSE file for copyright and license details. */
#include "internals.h"
void
zlsh(z_t a, z_t b, size_t bits)
{
size_t i, chars, cbits;
zahl_char_t carry[] = {0, 0};
if (unlikely(zzero(b))) {
SET_SIGNUM(a, 0);
return;
}
if (unlikely(!bits)) {
SET(a, b);
return;
}
chars = FLOOR_BITS_TO_CHARS(bits);
bits = BITS_IN_LAST_CHAR(bits);
cbits = BITS_PER_CHAR - bits;
ENSURE_SIZE(a, b->used + chars);
if (likely(a == b))
zmemmove(a->chars + chars, b->chars, b->used);
else
zmemcpy(a->chars + chars, b->chars, b->used);
zmemset(a->chars, 0, chars);
a->used = b->used + chars;
if (likely(bits)) { /* This if statement is very important in C. */
for (i = chars; i < a->used; i++) {
carry[~i & 1] = a->chars[i] >> cbits;
a->chars[i] <<= bits;
a->chars[i] |= carry[i & 1];
}
if (carry[i & 1]) {
ENSURE_SIZE(a, a->used + 1);
a->chars[i] = carry[i & 1];
a->used++;
}
}
SET_SIGNUM(a, zsignum(b));
}
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