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mode1o.asm revision 1.1.1.3 
      1 dnl  Intel P6 mpn_modexact_1_odd -- exact division style remainder.
      2 
      3 dnl  Copyright 2000-2002, 2007 Free Software Foundation, Inc.
      4 
      5 dnl  This file is part of the GNU MP Library.
      6 dnl
      7 dnl  The GNU MP Library is free software; you can redistribute it and/or modify
      8 dnl  it under the terms of either:
      9 dnl
     10 dnl    * the GNU Lesser General Public License as published by the Free
     11 dnl      Software Foundation; either version 3 of the License, or (at your
     12 dnl      option) any later version.
     13 dnl
     14 dnl  or
     15 dnl
     16 dnl    * the GNU General Public License as published by the Free Software
     17 dnl      Foundation; either version 2 of the License, or (at your option) any
     18 dnl      later version.
     19 dnl
     20 dnl  or both in parallel, as here.
     21 dnl
     22 dnl  The GNU MP Library is distributed in the hope that it will be useful, but
     23 dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
     24 dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     25 dnl  for more details.
     26 dnl
     27 dnl  You should have received copies of the GNU General Public License and the
     28 dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
     29 dnl  see https://www.gnu.org/licenses/.
     30 
     31 include(`../config.m4')
     32 
     33 
     34 C P6: 10.0 cycles/limb
     35 
     36 
     37 C mp_limb_t mpn_modexact_1_odd (mp_srcptr src, mp_size_t size,
     38 C                               mp_limb_t divisor);
     39 C mp_limb_t mpn_modexact_1c_odd (mp_srcptr src, mp_size_t size,
     40 C                                mp_limb_t divisor, mp_limb_t carry);
     41 C
     42 C It's not worth skipping a step at the end when high<divisor since the main
     43 C loop is only 10 cycles.
     44 
     45 defframe(PARAM_CARRY,  16)
     46 defframe(PARAM_DIVISOR,12)
     47 defframe(PARAM_SIZE,   8)
     48 defframe(PARAM_SRC,    4)
     49 
     50 dnl  Not enough room under modexact_1 to make these re-use the parameter
     51 dnl  space, unfortunately.
     52 defframe(SAVE_EBX,     -4)
     53 defframe(SAVE_ESI,     -8)
     54 defframe(SAVE_EDI,    -12)
     55 deflit(STACK_SPACE, 12)
     56 
     57 	TEXT
     58 
     59 	ALIGN(16)
     60 PROLOGUE(mpn_modexact_1c_odd)
     61 deflit(`FRAME',0)
     62 
     63 	movl	PARAM_CARRY, %ecx
     64 	jmp	L(start_1c)
     65 
     66 EPILOGUE()
     67 
     68 	ALIGN(16)
     69 PROLOGUE(mpn_modexact_1_odd)
     70 deflit(`FRAME',0)
     71 
     72 	xorl	%ecx, %ecx
     73 L(start_1c):
     74 	movl	PARAM_DIVISOR, %eax
     75 
     76 	subl	$STACK_SPACE, %esp	FRAME_subl_esp(STACK_SPACE)
     77 
     78 	movl	%esi, SAVE_ESI
     79 	movl	PARAM_SRC, %esi
     80 
     81 	shrl	%eax			C d/2
     82 	movl	%edi, SAVE_EDI
     83 
     84 	andl	$127, %eax
     85 
     86 ifdef(`PIC',`
     87 	LEA(	binvert_limb_table, %edi)
     88 	movzbl	(%eax,%edi), %edi		C inv 8 bits
     89 ',`
     90 	movzbl	binvert_limb_table(%eax), %edi	C inv 8 bits
     91 ')
     92 
     93 	xorl	%edx, %edx		C initial extra carry
     94 	leal	(%edi,%edi), %eax	C 2*inv
     95 
     96 	imull	%edi, %edi		C inv*inv
     97 
     98 	movl	%ebx, SAVE_EBX
     99 	movl	PARAM_SIZE, %ebx
    100 
    101 	imull	PARAM_DIVISOR, %edi	C inv*inv*d
    102 
    103 	subl	%edi, %eax		C inv = 2*inv - inv*inv*d
    104 	leal	(%eax,%eax), %edi	C 2*inv
    105 
    106 	imull	%eax, %eax		C inv*inv
    107 
    108 	imull	PARAM_DIVISOR, %eax	C inv*inv*d
    109 
    110 	leal	(%esi,%ebx,4), %esi	C src end
    111 	negl	%ebx			C -size
    112 
    113 	subl	%eax, %edi		C inv = 2*inv - inv*inv*d
    114 
    115 	ASSERT(e,`	C d*inv == 1 mod 2^GMP_LIMB_BITS
    116 	movl	PARAM_DIVISOR, %eax
    117 	imull	%edi, %eax
    118 	cmpl	$1, %eax')
    119 
    120 
    121 C The dependent chain here is
    122 C
    123 C	subl	%edx, %eax       1
    124 C	imull	%edi, %eax       4
    125 C	mull	PARAM_DIVISOR    5
    126 C			       ----
    127 C	total			10
    128 C
    129 C and this is the measured speed.  No special scheduling is necessary, out
    130 C of order execution hides the load latency.
    131 
    132 L(top):
    133 	C eax	scratch (src limb)
    134 	C ebx	counter, limbs, negative
    135 	C ecx	carry bit, 0 or 1
    136 	C edx	carry limb, high of last product
    137 	C esi	&src[size]
    138 	C edi	inverse
    139 	C ebp
    140 
    141 	movl	(%esi,%ebx,4), %eax
    142 	subl	%ecx, %eax
    143 
    144 	sbbl	%ecx, %ecx
    145 	subl	%edx, %eax
    146 
    147 	sbbl	$0, %ecx
    148 
    149 	imull	%edi, %eax
    150 
    151 	negl	%ecx
    152 
    153 	mull	PARAM_DIVISOR
    154 
    155 	incl	%ebx
    156 	jnz	L(top)
    157 
    158 
    159 	movl	SAVE_ESI, %esi
    160 	leal	(%ecx,%edx), %eax
    161 
    162 	movl	SAVE_EDI, %edi
    163 
    164 	movl	SAVE_EBX, %ebx
    165 	addl	$STACK_SPACE, %esp
    166 
    167 	ret
    168 
    169 EPILOGUE()
    170 ASM_END()
    171