121 lines
3.0 KiB
ArmAsm
121 lines
3.0 KiB
ArmAsm
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; 29000 mpn_sub_n -- 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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; Copyright 1992, 1994, 2000 Free Software Foundation, Inc.
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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 Lesser General Public License as published by
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; the Free Software Foundation; either version 2.1 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 Lesser General Public
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; License for more details.
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; You should have received a copy of the GNU Lesser 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., 51 Franklin Street, Fifth Floor, Boston,
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; MA 02110-1301, USA.
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; INPUT PARAMETERS
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; res_ptr lr2
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; s1_ptr lr3
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; s2_ptr lr4
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; size lr5
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; We use the loadm/storem instructions and operate on chunks of 8
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; limbs/per iteration, until less than 8 limbs remain.
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; The 29k has no addition or subtraction instructions that doesn't
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; affect carry, so we need to save and restore that as soon as we
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; adjust the pointers. gr116 is used for this purpose. Note that
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; gr116==0 means that carry should be set.
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.sect .lit,lit
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.text
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.align 4
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.global ___gmpn_sub_n
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.word 0x60000
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___gmpn_sub_n:
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srl gr117,lr5,3
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sub gr118,gr117,1
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jmpt gr118,Ltail
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constn gr116,-1 ; init cy reg
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sub gr117,gr117,2 ; count for jmpfdec
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; Main loop working 8 limbs/iteration.
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Loop: mtsrim cr,(8-1)
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loadm 0,0,gr96,lr3
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add lr3,lr3,32
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mtsrim cr,(8-1)
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loadm 0,0,gr104,lr4
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add lr4,lr4,32
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subr gr116,gr116,0 ; restore carry
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subc gr96,gr96,gr104
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subc gr97,gr97,gr105
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subc gr98,gr98,gr106
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subc gr99,gr99,gr107
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subc gr100,gr100,gr108
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subc gr101,gr101,gr109
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subc gr102,gr102,gr110
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subc gr103,gr103,gr111
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subc gr116,gr116,gr116 ; gr116 = not(cy)
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mtsrim cr,(8-1)
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storem 0,0,gr96,lr2
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jmpfdec gr117,Loop
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add lr2,lr2,32
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; Code for the last up-to-7 limbs.
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; This code might look very strange, but it's hard to write it
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; differently without major slowdown.
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and lr5,lr5,(8-1)
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Ltail: sub gr118,lr5,1 ; count for CR
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jmpt gr118,Lend
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sub gr117,lr5,2 ; count for jmpfdec
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mtsr cr,gr118
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loadm 0,0,gr96,lr3
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mtsr cr,gr118
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loadm 0,0,gr104,lr4
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subr gr116,gr116,0 ; restore carry
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jmpfdec gr117,L1
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subc gr96,gr96,gr104
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jmp Lstore
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mtsr cr,gr118
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L1: jmpfdec gr117,L2
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subc gr97,gr97,gr105
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jmp Lstore
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mtsr cr,gr118
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L2: jmpfdec gr117,L3
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subc gr98,gr98,gr106
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jmp Lstore
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mtsr cr,gr118
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L3: jmpfdec gr117,L4
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subc gr99,gr99,gr107
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jmp Lstore
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mtsr cr,gr118
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L4: jmpfdec gr117,L5
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subc gr100,gr100,gr108
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jmp Lstore
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mtsr cr,gr118
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L5: jmpfdec gr117,L6
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subc gr101,gr101,gr109
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jmp Lstore
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mtsr cr,gr118
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L6: subc gr102,gr102,gr110
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Lstore: storem 0,0,gr96,lr2
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subc gr116,gr116,gr116 ; gr116 = not(cy)
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Lend: jmpi lr0
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add gr96,gr116,1
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