Page 236 - ARM 64 Bit Assembly Language

224 Chapter 7

489 else
490 tmp->blks[i]=l->blks[i-chunks];
491 }
492 return tmp;
493 }
494
495 /* Shift left the given about. This will shift by chunks as much as
496 it can, then finish off with a sub-chunk shift. */
497 bigint bigint_shift_left(bigint l, int shamt) {
498 bigint tmp;
499 l = bigint_extend(l, l->size+1);
500 int extra = shamt % BITSPERCHUNK;
501 shamt = shamt / BITSPERCHUNK;
502 if (shamt) {
503 tmp=l;
504 l = bigint_shift_left_chunk(l, shamt);
505 bigint_free(tmp);
506 }
507 if (extra) {
508 for (int i = l->size - 1; i > 0; i--) {
509 l->blks[i] =
510 (l->blks[i]<<extra) | (l->blks[i-1]>>(BITSPERCHUNK-extra));
511 }
512 l->blks[0] = (l->blks[0] << extra);
513 }
514 tmp = bigint_trim(l);
515 bigint_free(l);
516 return tmp;
517 }
518
519 /* Arithmetic shift right the given about. This will shift by
520 chunks as much as it can, then finish off with a sub-chunk
521 shift. */
522 bigint bigint_shift_right(bigint l, int shamt) {
523 bigint tmp;
524 schunk tmpc;
525 int extra = shamt % BITSPERCHUNK;
526 shamt = shamt / BITSPERCHUNK;
527 l = bigint_shift_right_chunk(l, shamt);
528 if (extra) {
529 for (int i = 0; i < l->size-1; i++) {
530 l->blks[i] =
531 (l->blks[i]>>extra) | (l->blks[i+1]<<(BITSPERCHUNK-extra));
532 }
533 /* do a signed shift of the top chunk */
534 tmpc = l->blks[l->size - 1];
535 tmpc >>= extra;
536 l->blks[l->size - 1] = tmpc;
537 }