1; mc88100 __gmpn_mul_1 -- Multiply a limb vector with a single limb and 2; store the product in a second limb vector. 3 4; Copyright 1992, 1994, 1995, 2000 Free Software Foundation, Inc. 5 6; This file is part of the GNU MP Library. 7 8; The GNU MP Library is free software; you can redistribute it and/or modify 9; it under the terms of the GNU Lesser General Public License as published by 10; the Free Software Foundation; either version 3 of the License, or (at your 11; option) any later version. 12 13; The GNU MP Library is distributed in the hope that it will be useful, but 14; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16; License for more details. 17 18; You should have received a copy of the GNU Lesser General Public License 19; along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. 20 21 22; INPUT PARAMETERS 23; res_ptr r2 24; s1_ptr r3 25; size r4 26; s2_limb r5 27 28; Common overhead is about 11 cycles/invocation. 29 30; The speed for S2_LIMB >= 0x10000 is approximately 21 cycles/limb. (The 31; pipeline stalls 2 cycles due to WB contention.) 32 33; The speed for S2_LIMB < 0x10000 is approximately 16 cycles/limb. (The 34; pipeline stalls 2 cycles due to WB contention and 1 cycle due to latency.) 35 36; To enhance speed: 37; 1. Unroll main loop 4-8 times. 38; 2. Schedule code to avoid WB contention. It might be tempting to move the 39; ld instruction in the loops down to save 2 cycles (less WB contention), 40; but that looses because the ultimate value will be read from outside 41; the allocated space. But if we handle the ultimate multiplication in 42; the tail, we can do this. 43; 3. Make the multiplication with less instructions. I think the code for 44; (S2_LIMB >= 0x10000) is not minimal. 45; With these techniques the (S2_LIMB >= 0x10000) case would run in 17 or 46; less cycles/limb; the (S2_LIMB < 0x10000) case would run in 11 47; cycles/limb. (Assuming infinite unrolling.) 48 49 text 50 align 16 51 global ___gmpn_mul_1 52___gmpn_mul_1: 53 54 ; Make S1_PTR and RES_PTR point at the end of their blocks 55 ; and negate SIZE. 56 lda r3,r3[r4] 57 lda r6,r2[r4] ; RES_PTR in r6 since r2 is retval 58 subu r4,r0,r4 59 60 addu.co r2,r0,r0 ; r2 = cy = 0 61 ld r9,r3[r4] 62 mask r7,r5,0xffff ; r7 = lo(S2_LIMB) 63 extu r8,r5,16 ; r8 = hi(S2_LIMB) 64 bcnd.n eq0,r8,Lsmall ; jump if (hi(S2_LIMB) == 0) 65 subu r6,r6,4 66 67; General code for any value of S2_LIMB. 68 69 ; Make a stack frame and save r25 and r26 70 subu r31,r31,16 71 st.d r25,r31,8 72 73 ; Enter the loop in the middle 74 br.n L1 75 addu r4,r4,1 76 77Loop: ld r9,r3[r4] 78 st r26,r6[r4] 79; bcnd ne0,r0,0 ; bubble 80 addu r4,r4,1 81L1: mul r26,r9,r5 ; low word of product mul_1 WB ld 82 mask r12,r9,0xffff ; r12 = lo(s1_limb) mask_1 83 mul r11,r12,r7 ; r11 = prod_0 mul_2 WB mask_1 84 mul r10,r12,r8 ; r10 = prod_1a mul_3 85 extu r13,r9,16 ; r13 = hi(s1_limb) extu_1 WB mul_1 86 mul r12,r13,r7 ; r12 = prod_1b mul_4 WB extu_1 87 mul r25,r13,r8 ; r25 = prod_2 mul_5 WB mul_2 88 extu r11,r11,16 ; r11 = hi(prod_0) extu_2 WB mul_3 89 addu r10,r10,r11 ; addu_1 WB extu_2 90; bcnd ne0,r0,0 ; bubble WB addu_1 91 addu.co r10,r10,r12 ; WB mul_4 92 mask.u r10,r10,0xffff ; move the 16 most significant bits... 93 addu.ci r10,r10,r0 ; ...to the low half of the word... 94 rot r10,r10,16 ; ...and put carry in pos 16. 95 addu.co r26,r26,r2 ; add old carry limb 96 bcnd.n ne0,r4,Loop 97 addu.ci r2,r25,r10 ; compute new carry limb 98 99 st r26,r6[r4] 100 ld.d r25,r31,8 101 jmp.n r1 102 addu r31,r31,16 103 104; Fast code for S2_LIMB < 0x10000 105Lsmall: 106 ; Enter the loop in the middle 107 br.n SL1 108 addu r4,r4,1 109 110SLoop: ld r9,r3[r4] ; 111 st r8,r6[r4] ; 112 addu r4,r4,1 ; 113SL1: mul r8,r9,r5 ; low word of product 114 mask r12,r9,0xffff ; r12 = lo(s1_limb) 115 extu r13,r9,16 ; r13 = hi(s1_limb) 116 mul r11,r12,r7 ; r11 = prod_0 117 mul r12,r13,r7 ; r12 = prod_1b 118 addu.cio r8,r8,r2 ; add old carry limb 119 extu r10,r11,16 ; r11 = hi(prod_0) 120 addu r10,r10,r12 ; 121 bcnd.n ne0,r4,SLoop 122 extu r2,r10,16 ; r2 = new carry limb 123 124 jmp.n r1 125 st r8,r6[r4] 126