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