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-rw-r--r--lib/mpi/mpih-div.c309
1 files changed, 0 insertions, 309 deletions
diff --git a/lib/mpi/mpih-div.c b/lib/mpi/mpih-div.c
index cde1aaec18da..c57d1d46295e 100644
--- a/lib/mpi/mpih-div.c
+++ b/lib/mpi/mpih-div.c
@@ -37,159 +37,6 @@
37#define UDIV_TIME UMUL_TIME 37#define UDIV_TIME UMUL_TIME
38#endif 38#endif
39 39
40/* FIXME: We should be using invert_limb (or invert_normalized_limb)
41 * here (not udiv_qrnnd).
42 */
43
44mpi_limb_t
45mpihelp_mod_1(mpi_ptr_t dividend_ptr, mpi_size_t dividend_size,
46 mpi_limb_t divisor_limb)
47{
48 mpi_size_t i;
49 mpi_limb_t n1, n0, r;
50 int dummy;
51
52 /* Botch: Should this be handled at all? Rely on callers? */
53 if (!dividend_size)
54 return 0;
55
56 /* If multiplication is much faster than division, and the
57 * dividend is large, pre-invert the divisor, and use
58 * only multiplications in the inner loop.
59 *
60 * This test should be read:
61 * Does it ever help to use udiv_qrnnd_preinv?
62 * && Does what we save compensate for the inversion overhead?
63 */
64 if (UDIV_TIME > (2 * UMUL_TIME + 6)
65 && (UDIV_TIME - (2 * UMUL_TIME + 6)) * dividend_size > UDIV_TIME) {
66 int normalization_steps;
67
68 count_leading_zeros(normalization_steps, divisor_limb);
69 if (normalization_steps) {
70 mpi_limb_t divisor_limb_inverted;
71
72 divisor_limb <<= normalization_steps;
73
74 /* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB. The
75 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the
76 * most significant bit (with weight 2**N) implicit.
77 *
78 * Special case for DIVISOR_LIMB == 100...000.
79 */
80 if (!(divisor_limb << 1))
81 divisor_limb_inverted = ~(mpi_limb_t) 0;
82 else
83 udiv_qrnnd(divisor_limb_inverted, dummy,
84 -divisor_limb, 0, divisor_limb);
85
86 n1 = dividend_ptr[dividend_size - 1];
87 r = n1 >> (BITS_PER_MPI_LIMB - normalization_steps);
88
89 /* Possible optimization:
90 * if (r == 0
91 * && divisor_limb > ((n1 << normalization_steps)
92 * | (dividend_ptr[dividend_size - 2] >> ...)))
93 * ...one division less...
94 */
95 for (i = dividend_size - 2; i >= 0; i--) {
96 n0 = dividend_ptr[i];
97 UDIV_QRNND_PREINV(dummy, r, r,
98 ((n1 << normalization_steps)
99 | (n0 >>
100 (BITS_PER_MPI_LIMB -
101 normalization_steps))),
102 divisor_limb,
103 divisor_limb_inverted);
104 n1 = n0;
105 }
106 UDIV_QRNND_PREINV(dummy, r, r,
107 n1 << normalization_steps,
108 divisor_limb, divisor_limb_inverted);
109 return r >> normalization_steps;
110 } else {
111 mpi_limb_t divisor_limb_inverted;
112
113 /* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB. The
114 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the
115 * most significant bit (with weight 2**N) implicit.
116 *
117 * Special case for DIVISOR_LIMB == 100...000.
118 */
119 if (!(divisor_limb << 1))
120 divisor_limb_inverted = ~(mpi_limb_t) 0;
121 else
122 udiv_qrnnd(divisor_limb_inverted, dummy,
123 -divisor_limb, 0, divisor_limb);
124
125 i = dividend_size - 1;
126 r = dividend_ptr[i];
127
128 if (r >= divisor_limb)
129 r = 0;
130 else
131 i--;
132
133 for (; i >= 0; i--) {
134 n0 = dividend_ptr[i];
135 UDIV_QRNND_PREINV(dummy, r, r,
136 n0, divisor_limb,
137 divisor_limb_inverted);
138 }
139 return r;
140 }
141 } else {
142 if (UDIV_NEEDS_NORMALIZATION) {
143 int normalization_steps;
144
145 count_leading_zeros(normalization_steps, divisor_limb);
146 if (normalization_steps) {
147 divisor_limb <<= normalization_steps;
148
149 n1 = dividend_ptr[dividend_size - 1];
150 r = n1 >> (BITS_PER_MPI_LIMB -
151 normalization_steps);
152
153 /* Possible optimization:
154 * if (r == 0
155 * && divisor_limb > ((n1 << normalization_steps)
156 * | (dividend_ptr[dividend_size - 2] >> ...)))
157 * ...one division less...
158 */
159 for (i = dividend_size - 2; i >= 0; i--) {
160 n0 = dividend_ptr[i];
161 udiv_qrnnd(dummy, r, r,
162 ((n1 << normalization_steps)
163 | (n0 >>
164 (BITS_PER_MPI_LIMB -
165 normalization_steps))),
166 divisor_limb);
167 n1 = n0;
168 }
169 udiv_qrnnd(dummy, r, r,
170 n1 << normalization_steps,
171 divisor_limb);
172 return r >> normalization_steps;
173 }
174 }
175 /* No normalization needed, either because udiv_qrnnd doesn't require
176 * it, or because DIVISOR_LIMB is already normalized. */
177 i = dividend_size - 1;
178 r = dividend_ptr[i];
179
180 if (r >= divisor_limb)
181 r = 0;
182 else
183 i--;
184
185 for (; i >= 0; i--) {
186 n0 = dividend_ptr[i];
187 udiv_qrnnd(dummy, r, r, n0, divisor_limb);
188 }
189 return r;
190 }
191}
192
193/* Divide num (NP/NSIZE) by den (DP/DSIZE) and write 40/* Divide num (NP/NSIZE) by den (DP/DSIZE) and write
194 * the NSIZE-DSIZE least significant quotient limbs at QP 41 * the NSIZE-DSIZE least significant quotient limbs at QP
195 * and the DSIZE long remainder at NP. If QEXTRA_LIMBS is 42 * and the DSIZE long remainder at NP. If QEXTRA_LIMBS is
@@ -387,159 +234,3 @@ q_test:
387 234
388 return most_significant_q_limb; 235 return most_significant_q_limb;
389} 236}
390
391/****************
392 * Divide (DIVIDEND_PTR,,DIVIDEND_SIZE) by DIVISOR_LIMB.
393 * Write DIVIDEND_SIZE limbs of quotient at QUOT_PTR.
394 * Return the single-limb remainder.
395 * There are no constraints on the value of the divisor.
396 *
397 * QUOT_PTR and DIVIDEND_PTR might point to the same limb.
398 */
399
400mpi_limb_t
401mpihelp_divmod_1(mpi_ptr_t quot_ptr,
402 mpi_ptr_t dividend_ptr, mpi_size_t dividend_size,
403 mpi_limb_t divisor_limb)
404{
405 mpi_size_t i;
406 mpi_limb_t n1, n0, r;
407 int dummy;
408
409 if (!dividend_size)
410 return 0;
411
412 /* If multiplication is much faster than division, and the
413 * dividend is large, pre-invert the divisor, and use
414 * only multiplications in the inner loop.
415 *
416 * This test should be read:
417 * Does it ever help to use udiv_qrnnd_preinv?
418 * && Does what we save compensate for the inversion overhead?
419 */
420 if (UDIV_TIME > (2 * UMUL_TIME + 6)
421 && (UDIV_TIME - (2 * UMUL_TIME + 6)) * dividend_size > UDIV_TIME) {
422 int normalization_steps;
423
424 count_leading_zeros(normalization_steps, divisor_limb);
425 if (normalization_steps) {
426 mpi_limb_t divisor_limb_inverted;
427
428 divisor_limb <<= normalization_steps;
429
430 /* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB. The
431 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the
432 * most significant bit (with weight 2**N) implicit.
433 */
434 /* Special case for DIVISOR_LIMB == 100...000. */
435 if (!(divisor_limb << 1))
436 divisor_limb_inverted = ~(mpi_limb_t) 0;
437 else
438 udiv_qrnnd(divisor_limb_inverted, dummy,
439 -divisor_limb, 0, divisor_limb);
440
441 n1 = dividend_ptr[dividend_size - 1];
442 r = n1 >> (BITS_PER_MPI_LIMB - normalization_steps);
443
444 /* Possible optimization:
445 * if (r == 0
446 * && divisor_limb > ((n1 << normalization_steps)
447 * | (dividend_ptr[dividend_size - 2] >> ...)))
448 * ...one division less...
449 */
450 for (i = dividend_size - 2; i >= 0; i--) {
451 n0 = dividend_ptr[i];
452 UDIV_QRNND_PREINV(quot_ptr[i + 1], r, r,
453 ((n1 << normalization_steps)
454 | (n0 >>
455 (BITS_PER_MPI_LIMB -
456 normalization_steps))),
457 divisor_limb,
458 divisor_limb_inverted);
459 n1 = n0;
460 }
461 UDIV_QRNND_PREINV(quot_ptr[0], r, r,
462 n1 << normalization_steps,
463 divisor_limb, divisor_limb_inverted);
464 return r >> normalization_steps;
465 } else {
466 mpi_limb_t divisor_limb_inverted;
467
468 /* Compute (2**2N - 2**N * DIVISOR_LIMB) / DIVISOR_LIMB. The
469 * result is a (N+1)-bit approximation to 1/DIVISOR_LIMB, with the
470 * most significant bit (with weight 2**N) implicit.
471 */
472 /* Special case for DIVISOR_LIMB == 100...000. */
473 if (!(divisor_limb << 1))
474 divisor_limb_inverted = ~(mpi_limb_t) 0;
475 else
476 udiv_qrnnd(divisor_limb_inverted, dummy,
477 -divisor_limb, 0, divisor_limb);
478
479 i = dividend_size - 1;
480 r = dividend_ptr[i];
481
482 if (r >= divisor_limb)
483 r = 0;
484 else
485 quot_ptr[i--] = 0;
486
487 for (; i >= 0; i--) {
488 n0 = dividend_ptr[i];
489 UDIV_QRNND_PREINV(quot_ptr[i], r, r,
490 n0, divisor_limb,
491 divisor_limb_inverted);
492 }
493 return r;
494 }
495 } else {
496 if (UDIV_NEEDS_NORMALIZATION) {
497 int normalization_steps;
498
499 count_leading_zeros(normalization_steps, divisor_limb);
500 if (normalization_steps) {
501 divisor_limb <<= normalization_steps;
502
503 n1 = dividend_ptr[dividend_size - 1];
504 r = n1 >> (BITS_PER_MPI_LIMB -
505 normalization_steps);
506
507 /* Possible optimization:
508 * if (r == 0
509 * && divisor_limb > ((n1 << normalization_steps)
510 * | (dividend_ptr[dividend_size - 2] >> ...)))
511 * ...one division less...
512 */
513 for (i = dividend_size - 2; i >= 0; i--) {
514 n0 = dividend_ptr[i];
515 udiv_qrnnd(quot_ptr[i + 1], r, r,
516 ((n1 << normalization_steps)
517 | (n0 >>
518 (BITS_PER_MPI_LIMB -
519 normalization_steps))),
520 divisor_limb);
521 n1 = n0;
522 }
523 udiv_qrnnd(quot_ptr[0], r, r,
524 n1 << normalization_steps,
525 divisor_limb);
526 return r >> normalization_steps;
527 }
528 }
529 /* No normalization needed, either because udiv_qrnnd doesn't require
530 * it, or because DIVISOR_LIMB is already normalized. */
531 i = dividend_size - 1;
532 r = dividend_ptr[i];
533
534 if (r >= divisor_limb)
535 r = 0;
536 else
537 quot_ptr[i--] = 0;
538
539 for (; i >= 0; i--) {
540 n0 = dividend_ptr[i];
541 udiv_qrnnd(quot_ptr[i], r, r, n0, divisor_limb);
542 }
543 return r;
544 }
545}
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