mode1o.asm
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- dnl PowerPC-32 mpn_modexact_1_odd -- mpn by limb exact remainder.
- dnl Copyright 2002, 2003, 2005, 2006 Free Software Foundation, Inc.
- dnl
- dnl This file is part of the GNU MP Library.
- dnl
- dnl The GNU MP Library is free software; you can redistribute it and/or
- dnl modify it under the terms of the GNU Lesser General Public License as
- dnl published by the Free Software Foundation; either version 3 of the
- dnl License, or (at your option) any later version.
- dnl
- dnl The GNU MP Library is distributed in the hope that it will be useful,
- dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
- dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- dnl Lesser General Public License for more details.
- dnl
- dnl You should have received a copy of the GNU Lesser General Public License
- dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/.
- include(`../config.m4')
- C cycles/limb
- C 603e: ?
- C 604e: 6.0
- C 75x (G3): 6.0-13.0, depending on divisor
- C 7400,7410 (G4): 6.0-13.0, depending on divisor
- C 744x,745x (G4+): 8.0-10.0, depending on divisor
- C power4/ppc970: 12.0
- C power5: 12.0
- C mp_limb_t mpn_modexact_1_odd (mp_srcptr src, mp_size_t size,
- C mp_limb_t divisor);
- C mp_limb_t mpn_modexact_1c_odd (mp_srcptr src, mp_size_t size,
- C mp_limb_t divisor, mp_limb_t carry);
- C
- C For PIC, the inverse is established arithmetically since it measures about
- C 5 cycles faster than the nonsense needed to access binvert_limb_table in
- C SVR4 or Darwin style PIC. AIX might be better, since it avoids bl/mflr to
- C get at the GOT/TOC/whatever.
- C
- C Using divwu for size==1 measured about 10 cycles slower on 604e, or about
- C 3-5 cycles faster on 750. For now it doesn't seem worth bothering with.
- C
- C The loop allows an early-out on mullw for the inverse, and on mulhwu for
- C the divisor. So the fastest is for instance divisor==1 (inverse==-1), and
- C the slowest is anything giving a full 32-bits in both, such as
- C divisor==0xDEADBEEF (inverse==0x904B300F). These establish the stated
- C range above for 750 and 7400.
- ASM_START()
- EXTERN(binvert_limb_table)
- PROLOGUE(mpn_modexact_1_odd)
- li r6, 0
- PROLOGUE(mpn_modexact_1c_odd)
- mtctr r4 C size
- ifdef(`PIC_SLOW',`
- C Load from our table with PIC is so slow on Linux and Darwin that we avoid it
- rlwinm r7, r5, 1,28,28 C (divisor << 1) & 8
- rlwinm r8, r5, 2,28,28 C (divisor << 2) & 8
- xor r7, r7, r8 C ((divisor << 1) ^ (divisor << 2)) & 8
- rlwinm r4, r5, 0,28,31 C divisor low 4 bits, speedup mullw
- xor r4, r4, r7 C inverse, 4 bits
- mullw r7, r4, r4 C i*i
- slwi r4, r4, 1 C 2*i
- rlwinm r8, r5, 0,24,31 C divisor low 8 bits, speedup mullw
- mullw r7, r7, r8 C i*i*d
- sub r4, r4, r7 C inverse, 8 bits
- ',`
- LEA( r7, binvert_limb_table)
- rlwinm r4, r5, 31,25,31 C (divisor/2) & 0x7F
- lbzx r4, r4,r7 C inverse, 8 bits
- ')
- mullw r7, r4, r4 C i*i
- slwi r4, r4, 1 C 2*i
- mullw r7, r5, r7 C i*i*d [i*i is 16 bits, so second operand]
- sub r4, r4, r7 C inverse, 16 bits
- mullw r7, r4, r4 C i*i
- slwi r4, r4, 1 C 2*i
- mullw r7, r7, r5 C i*i*d
- lwz r0, 0(r3) C src[0]
- sub r4, r4, r7 C inverse, 32 bits
- subfc r7, r6, r0 C l = src[0] - carry
- mullw r7, r7, r4 C q = l * inverse
- bdz L(one)
- lwzu r0, 4(r3) C src[1]
- mulhwu r6, r7, r5 C carry = high(q*divisor)
- subfe r7, r6, r0 C l = src[1] - carry
- bdz L(two)
- L(top):
- mullw r7, r7, r4 C q = l * inverse
- lwzu r0, 4(r3) C src[i]
- mulhwu r6, r7, r5 C carry = high(q*divisor)
- subfe r7, r6, r0 C l = src[i] - carry
- bdnz L(top)
- L(two): mullw r7, r7, r4 C q = l * inverse
- L(one): subfe r3, r3, r3 C ca 0 or -1
- mulhwu r6, r7, r5 C carry = high(q*divisor)
- subf r3, r3, r6 C carry + ca
- blr
- EPILOGUE(mpn_modexact_1c_odd)
- EPILOGUE(mpn_modexact_1_odd)
- ASM_END()