1995-12-04 18:37:56 +00:00
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; mc88100 __mpn_sub -- Subtract two limb vectors of the same length > 0 and
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; store difference in a third limb vector.
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1996-03-01 18:45:35 +00:00
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; Copyright (C) 1992, 1994, 1996 Free Software Foundation, Inc.
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1995-12-04 18:37:56 +00:00
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; This file is part of the GNU MP Library.
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; The GNU MP Library is free software; you can redistribute it and/or modify
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; it under the terms of the GNU Library General Public License as published by
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; the Free Software Foundation; either version 2 of the License, or (at your
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; option) any later version.
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; The GNU MP Library is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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; License for more details.
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; You should have received a copy of the GNU Library General Public License
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; along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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; the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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; INPUT PARAMETERS
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; res_ptr r2
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; s1_ptr r3
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; s2_ptr r4
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; size r5
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; This code has been optimized to run one instruction per clock, avoiding
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; load stalls and writeback contention. As a result, the instruction
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; order is not always natural.
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; The speed is about 4.6 clocks/limb + 18 clocks/limb-vector on an 88100,
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; but on the 88110, it seems to run much slower, 6.6 clocks/limb.
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text
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align 16
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global ___mpn_sub_n
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___mpn_sub_n:
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ld r6,r3,0 ; read first limb from s1_ptr
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extu r10,r5,3
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ld r7,r4,0 ; read first limb from s2_ptr
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1996-03-01 18:45:35 +00:00
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subu r5,r0,r5
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1995-12-04 18:37:56 +00:00
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mak r5,r5,3<4>
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1996-03-01 18:45:35 +00:00
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bcnd.n eq0,r5,Lzero
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subu.co r0,r0,r0 ; initialize carry
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1995-12-04 18:37:56 +00:00
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or r12,r0,lo16(Lbase)
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or.u r12,r12,hi16(Lbase)
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addu r12,r12,r5 ; r12 is address for entering in loop
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extu r5,r5,2 ; divide by 4
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subu r2,r2,r5 ; adjust res_ptr
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subu r3,r3,r5 ; adjust s1_ptr
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subu r4,r4,r5 ; adjust s2_ptr
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or r8,r6,r0
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jmp.n r12
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or r9,r7,r0
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Loop: addu r3,r3,32
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st r8,r2,28
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addu r4,r4,32
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ld r6,r3,0
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addu r2,r2,32
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ld r7,r4,0
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Lzero: subu r10,r10,1 ; subtract 0 + 8r limbs (adj loop cnt)
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Lbase: ld r8,r3,4
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subu.cio r6,r6,r7
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ld r9,r4,4
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st r6,r2,0
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ld r6,r3,8 ; subtract 7 + 8r limbs
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subu.cio r8,r8,r9
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ld r7,r4,8
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st r8,r2,4
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ld r8,r3,12 ; subtract 6 + 8r limbs
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subu.cio r6,r6,r7
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ld r9,r4,12
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st r6,r2,8
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ld r6,r3,16 ; subtract 5 + 8r limbs
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subu.cio r8,r8,r9
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ld r7,r4,16
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st r8,r2,12
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ld r8,r3,20 ; subtract 4 + 8r limbs
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subu.cio r6,r6,r7
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ld r9,r4,20
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st r6,r2,16
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ld r6,r3,24 ; subtract 3 + 8r limbs
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subu.cio r8,r8,r9
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ld r7,r4,24
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st r8,r2,20
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ld r8,r3,28 ; subtract 2 + 8r limbs
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subu.cio r6,r6,r7
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ld r9,r4,28
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st r6,r2,24
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bcnd.n ne0,r10,Loop ; subtract 1 + 8r limbs
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subu.cio r8,r8,r9
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st r8,r2,28 ; store most significant limb
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addu.ci r2,r0,r0 ; return carry-out from most sign. limb
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jmp.n r1
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xor r2,r2,1
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