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Diffstat (limited to 'sysdeps/m88k/mul_1.s')
| -rw-r--r-- | sysdeps/m88k/mul_1.s | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/sysdeps/m88k/mul_1.s b/sysdeps/m88k/mul_1.s new file mode 100644 index 0000000000..35c238d570 --- /dev/null +++ b/sysdeps/m88k/mul_1.s @@ -0,0 +1,128 @@ +; mc88100 __mpn_mul_1 -- Multiply a limb vector with a single limb and +; store the product in a second limb vector. + +; Copyright (C) 1992, 1994 Free Software Foundation, Inc. + +; This file is part of the GNU MP Library. + +; The GNU MP Library is free software; you can redistribute it and/or modify +; it under the terms of the GNU Library General Public License as published by +; the Free Software Foundation; either version 2 of the License, or (at your +; option) any later version. + +; The GNU MP Library is distributed in the hope that it will be useful, but +; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public +; License for more details. + +; You should have received a copy of the GNU Library General Public License +; along with the GNU MP Library; see the file COPYING.LIB. If not, write to +; the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + +; INPUT PARAMETERS +; res_ptr r2 +; s1_ptr r3 +; size r4 +; s2_limb r5 + +; Common overhead is about 11 cycles/invocation. + +; The speed for S2_LIMB >= 0x10000 is approximately 21 cycles/limb. (The +; pipeline stalls 2 cycles due to WB contention.) + +; The speed for S2_LIMB < 0x10000 is approximately 16 cycles/limb. (The +; pipeline stalls 2 cycles due to WB contention and 1 cycle due to latency.) + +; To enhance speed: +; 1. Unroll main loop 4-8 times. +; 2. Schedule code to avoid WB contention. It might be tempting to move the +; ld instruction in the loops down to save 2 cycles (less WB contention), +; but that looses because the ultimate value will be read from outside +; the allocated space. But if we handle the ultimate multiplication in +; the tail, we can do this. +; 3. Make the multiplication with less instructions. I think the code for +; (S2_LIMB >= 0x10000) is not minimal. +; With these techniques the (S2_LIMB >= 0x10000) case would run in 17 or +; less cycles/limb; the (S2_LIMB < 0x10000) case would run in 11 +; cycles/limb. (Assuming infinite unrolling.) + + text + align 16 + global ___mpn_mul_1 +___mpn_mul_1: + + ; Make S1_PTR and RES_PTR point at the end of their blocks + ; and negate SIZE. + lda r3,r3[r4] + lda r6,r2[r4] ; RES_PTR in r6 since r2 is retval + subu r4,r0,r4 + + addu.co r2,r0,r0 ; r2 = cy = 0 + ld r9,r3[r4] + mask r7,r5,0xffff ; r7 = lo(S2_LIMB) + extu r8,r5,16 ; r8 = hi(S2_LIMB) + bcnd.n eq0,r8,Lsmall ; jump if (hi(S2_LIMB) == 0) + subu r6,r6,4 + +; General code for any value of S2_LIMB. + + ; Make a stack frame and save r25 and r26 + subu r31,r31,16 + st.d r25,r31,8 + + ; Enter the loop in the middle + br.n L1 + addu r4,r4,1 + +Loop: + ld r9,r3[r4] + st r26,r6[r4] +; bcnd ne0,r0,0 ; bubble + addu r4,r4,1 +L1: mul r26,r9,r5 ; low word of product mul_1 WB ld + mask r12,r9,0xffff ; r12 = lo(s1_limb) mask_1 + mul r11,r12,r7 ; r11 = prod_0 mul_2 WB mask_1 + mul r10,r12,r8 ; r10 = prod_1a mul_3 + extu r13,r9,16 ; r13 = hi(s1_limb) extu_1 WB mul_1 + mul r12,r13,r7 ; r12 = prod_1b mul_4 WB extu_1 + mul r25,r13,r8 ; r25 = prod_2 mul_5 WB mul_2 + extu r11,r11,16 ; r11 = hi(prod_0) extu_2 WB mul_3 + addu r10,r10,r11 ; addu_1 WB extu_2 +; bcnd ne0,r0,0 ; bubble WB addu_1 + addu.co r10,r10,r12 ; WB mul_4 + mask.u r10,r10,0xffff ; move the 16 most significant bits... + addu.ci r10,r10,r0 ; ...to the low half of the word... + rot r10,r10,16 ; ...and put carry in pos 16. + addu.co r26,r26,r2 ; add old carry limb + bcnd.n ne0,r4,Loop + addu.ci r2,r25,r10 ; compute new carry limb + + st r26,r6[r4] + ld.d r25,r31,8 + jmp.n r1 + addu r31,r31,16 + +; Fast code for S2_LIMB < 0x10000 +Lsmall: + ; Enter the loop in the middle + br.n SL1 + addu r4,r4,1 + +SLoop: + ld r9,r3[r4] ; + st r8,r6[r4] ; + addu r4,r4,1 ; +SL1: mul r8,r9,r5 ; low word of product + mask r12,r9,0xffff ; r12 = lo(s1_limb) + extu r13,r9,16 ; r13 = hi(s1_limb) + mul r11,r12,r7 ; r11 = prod_0 + mul r12,r13,r7 ; r12 = prod_1b + addu.cio r8,r8,r2 ; add old carry limb + extu r10,r11,16 ; r11 = hi(prod_0) + addu r10,r10,r12 ; + bcnd.n ne0,r4,SLoop + extu r2,r10,16 ; r2 = new carry limb + + jmp.n r1 + st r8,r6[r4] |