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fe62ba37a3
Written from scratch rather than copied from GMP, due to LGPL 2.1 vs GPL 3, but tested with the GMP testsuite. This is 50% faster than the generic code as measured on Cortex-A15. It is 25% slower than the current GMP routine on the same core.
69 lines
1.8 KiB
ArmAsm
69 lines
1.8 KiB
ArmAsm
/* mpn_submul_1 -- multiply and subtract bignums.
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Copyright (C) 2013 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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.syntax unified
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.text
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@ cycles/limb
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@ StrongArm ?
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@ Cortex-A8 ?
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@ Cortex-A9 ?
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@ Cortex-A15 4
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/* mp_limb_t mpn_submul_1(res_ptr, src1_ptr, size, s2_limb) */
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ENTRY (__mpn_submul_1)
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push { r4, r5, r6, r7 }
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cfi_adjust_cfa_offset (16)
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cfi_rel_offset (r4, 0)
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cfi_rel_offset (r5, 4)
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cfi_rel_offset (r6, 8)
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cfi_rel_offset (r7, 12)
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ldr r6, [r1], #4
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ldr r7, [r0]
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mov r4, #0 /* init carry in */
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b 1f
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0:
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ldr r6, [r1], #4 /* load next ul */
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adds r5, r5, r4 /* (lpl, c) = lpl + cl */
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adc r4, ip, #0 /* cl = hpl + c */
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subs r5, r7, r5 /* (lpl, !c) = rl - lpl */
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ldr r7, [r0, #4] /* load next rl */
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it cc
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addcc r4, r4, #1 /* cl += !c */
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str r5, [r0], #4
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1:
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umull r5, ip, r6, r3 /* (hpl, lpl) = ul * vl */
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subs r2, r2, #1
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bne 0b
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adds r5, r5, r4 /* (lpl, c) = lpl + cl */
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adc r4, ip, #0 /* cl = hpl + c */
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subs r5, r7, r5 /* (lpl, !c) = rl - lpl */
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str r5, [r0], #4
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it cc
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addcc r4, r4, #1 /* cl += !c */
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mov r0, r4 /* return carry */
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pop { r4, r5, r6, r7 }
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DO_RET (lr)
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END (__mpn_submul_1)
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