1dnl Intel Pentium mpn_mul_2 -- mpn by 2-limb multiplication. 2 3dnl Copyright 2001, 2002 Free Software Foundation, Inc. 4dnl 5dnl This file is part of the GNU MP Library. 6dnl 7dnl The GNU MP Library is free software; you can redistribute it and/or 8dnl modify it under the terms of the GNU Lesser General Public License as 9dnl published by the Free Software Foundation; either version 3 of the 10dnl License, or (at your option) any later version. 11dnl 12dnl The GNU MP Library is distributed in the hope that it will be useful, 13dnl but WITHOUT ANY WARRANTY; without even the implied warranty of 14dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15dnl Lesser General Public License for more details. 16dnl 17dnl You should have received a copy of the GNU Lesser General Public License 18dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. 19 20include(`../config.m4') 21 22 23C P5: 24.0 cycles/limb 24 25 26C mp_limb_t mpn_mul_2 (mp_ptr dst, mp_srcptr src, mp_size_t size, 27C mp_srcptr mult); 28C 29C At 24 c/l this is only 2 cycles faster than a separate mul_1 and addmul_1, 30C but has the advantage of making just one pass over the operands. 31C 32C There's not enough registers to use PARAM_MULT directly, so the multiplier 33C limbs are transferred to local variables on the stack. 34 35defframe(PARAM_MULT, 16) 36defframe(PARAM_SIZE, 12) 37defframe(PARAM_SRC, 8) 38defframe(PARAM_DST, 4) 39 40dnl re-use parameter space 41define(VAR_MULT_LOW, `PARAM_SRC') 42define(VAR_MULT_HIGH,`PARAM_DST') 43 44 TEXT 45 ALIGN(8) 46PROLOGUE(mpn_mul_2) 47deflit(`FRAME',0) 48 49 pushl %esi FRAME_pushl() 50 pushl %edi FRAME_pushl() 51 52 movl PARAM_SRC, %esi 53 movl PARAM_DST, %edi 54 55 movl PARAM_MULT, %eax 56 movl PARAM_SIZE, %ecx 57 58 movl 4(%eax), %edx C mult high 59 movl (%eax), %eax C mult low 60 61 movl %eax, VAR_MULT_LOW 62 movl %edx, VAR_MULT_HIGH 63 64 pushl %ebx FRAME_pushl() 65 pushl %ebp FRAME_pushl() 66 67 mull (%esi) C src[0] * mult[0] 68 69 movl %eax, %ebp C in case src==dst 70 movl (%esi), %eax C src[0] 71 72 movl %ebp, (%edi) C dst[0] 73 movl %edx, %ebx C initial low carry 74 75 xorl %ebp, %ebp C initial high carry 76 leal (%edi,%ecx,4), %edi C dst end 77 78 mull VAR_MULT_HIGH C src[0] * mult[1] 79 80 subl $2, %ecx C size-2 81 js L(done) 82 83 leal 8(%esi,%ecx,4), %esi C &src[size] 84 xorl $-1, %ecx C -(size-1) 85 86 87 88L(top): 89 C eax low prod 90 C ebx low carry 91 C ecx counter, negative 92 C edx high prod 93 C esi src end 94 C edi dst end 95 C ebp high carry (0 or -1) 96 97 andl $1, %ebp C 1 or 0 98 addl %eax, %ebx 99 100 adcl %edx, %ebp 101 ASSERT(nc) 102 movl (%esi,%ecx,4), %eax 103 104 mull VAR_MULT_LOW 105 106 addl %eax, %ebx C low carry 107 movl (%esi,%ecx,4), %eax 108 109 adcl %ebp, %edx C high carry 110 movl %ebx, (%edi,%ecx,4) 111 112 sbbl %ebp, %ebp C new high carry, -1 or 0 113 movl %edx, %ebx C new low carry 114 115 mull VAR_MULT_HIGH 116 117 incl %ecx 118 jnz L(top) 119 120 121L(done): 122 andl $1, %ebp C 1 or 0 123 addl %ebx, %eax 124 125 adcl %ebp, %edx 126 ASSERT(nc) 127 movl %eax, (%edi) C store carry low 128 129 movl %edx, %eax C return carry high 130 131 popl %ebp 132 popl %ebx 133 134 popl %edi 135 popl %esi 136 137 ret 138 139EPILOGUE() 140