mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-22 10:50:07 +00:00
128 lines
4.0 KiB
ArmAsm
128 lines
4.0 KiB
ArmAsm
; 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, 1995 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 Lesser General Public License as published by
|
|
; the Free Software Foundation; either version 2.1 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 Lesser General Public
|
|
; License for more details.
|
|
|
|
; You should have received a copy of the GNU Lesser General Public License
|
|
; along with the GNU MP Library; see the file COPYING.LIB. If not, write to
|
|
; the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
|
|
; MA 02111-1307, 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]
|