--- /dev/null
+dnl AMD K7 mpn_divexact_1 -- mpn by limb exact division.
+
+dnl Copyright 2001, 2002, 2004, 2007 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 Athlon: 11.0
+C Hammer: 9.0
+
+
+C void mpn_divexact_1 (mp_ptr dst, mp_srcptr src, mp_size_t size,
+C mp_limb_t divisor);
+C
+C The dependent chain is mul+imul+sub for 11 cycles and that speed is
+C achieved with no special effort. The load and shrld latencies are hidden
+C by out of order execution.
+C
+C It's a touch faster on size==1 to use the mul-by-inverse than divl.
+
+defframe(PARAM_DIVISOR,16)
+defframe(PARAM_SIZE, 12)
+defframe(PARAM_SRC, 8)
+defframe(PARAM_DST, 4)
+
+defframe(SAVE_EBX, -4)
+defframe(SAVE_ESI, -8)
+defframe(SAVE_EDI, -12)
+defframe(SAVE_EBP, -16)
+defframe(VAR_INVERSE, -20)
+defframe(VAR_DST_END, -24)
+
+deflit(STACK_SPACE, 24)
+
+ TEXT
+
+ ALIGN(16)
+PROLOGUE(mpn_divexact_1)
+deflit(`FRAME',0)
+
+ movl PARAM_DIVISOR, %eax
+ subl $STACK_SPACE, %esp deflit(`FRAME',STACK_SPACE)
+ movl $-1, %ecx C shift count
+
+ movl %ebp, SAVE_EBP
+ movl PARAM_SIZE, %ebp
+
+ movl %esi, SAVE_ESI
+ movl %edi, SAVE_EDI
+
+ C If there's usually only one or two trailing zero bits then this
+ C should be faster than bsfl.
+L(strip_twos):
+ incl %ecx
+ shrl %eax
+ jnc L(strip_twos)
+
+ movl %ebx, SAVE_EBX
+ leal 1(%eax,%eax), %ebx C d without twos
+ andl $127, %eax C d/2, 7 bits
+
+ifdef(`PIC',`
+ LEA( binvert_limb_table, %edx)
+ movzbl (%eax,%edx), %eax C inv 8 bits
+',`
+ movzbl binvert_limb_table(%eax), %eax C inv 8 bits
+')
+
+ leal (%eax,%eax), %edx C 2*inv
+ movl %ebx, PARAM_DIVISOR C d without twos
+
+ imull %eax, %eax C inv*inv
+
+ movl PARAM_SRC, %esi
+ movl PARAM_DST, %edi
+
+ imull %ebx, %eax C inv*inv*d
+
+ subl %eax, %edx C inv = 2*inv - inv*inv*d
+ leal (%edx,%edx), %eax C 2*inv
+
+ imull %edx, %edx C inv*inv
+
+ leal (%esi,%ebp,4), %esi C src end
+ leal (%edi,%ebp,4), %edi C dst end
+ negl %ebp C -size
+
+ imull %ebx, %edx C inv*inv*d
+
+ subl %edx, %eax C inv = 2*inv - inv*inv*d
+
+ ASSERT(e,` C expect d*inv == 1 mod 2^BITS_PER_MP_LIMB
+ pushl %eax FRAME_pushl()
+ imull PARAM_DIVISOR, %eax
+ cmpl $1, %eax
+ popl %eax FRAME_popl()')
+
+ movl %eax, VAR_INVERSE
+ movl (%esi,%ebp,4), %eax C src[0]
+
+ incl %ebp
+ jz L(one)
+
+ movl (%esi,%ebp,4), %edx C src[1]
+
+ shrdl( %cl, %edx, %eax)
+
+ movl %edi, VAR_DST_END
+ xorl %ebx, %ebx
+ jmp L(entry)
+
+ ALIGN(8)
+L(top):
+ C eax q
+ C ebx carry bit, 0 or 1
+ C ecx shift
+ C edx
+ C esi src end
+ C edi dst end
+ C ebp counter, limbs, negative
+
+ mull PARAM_DIVISOR C carry limb in edx
+
+ movl -4(%esi,%ebp,4), %eax
+ movl (%esi,%ebp,4), %edi
+
+ shrdl( %cl, %edi, %eax)
+
+ subl %ebx, %eax C apply carry bit
+ setc %bl
+ movl VAR_DST_END, %edi
+
+ subl %edx, %eax C apply carry limb
+ adcl $0, %ebx
+
+L(entry):
+ imull VAR_INVERSE, %eax
+
+ movl %eax, -4(%edi,%ebp,4)
+ incl %ebp
+ jnz L(top)
+
+
+ mull PARAM_DIVISOR C carry limb in edx
+
+ movl -4(%esi), %eax C src high limb
+ shrl %cl, %eax
+ movl SAVE_ESI, %esi
+
+ subl %ebx, %eax C apply carry bit
+ movl SAVE_EBX, %ebx
+ movl SAVE_EBP, %ebp
+
+ subl %edx, %eax C apply carry limb
+
+ imull VAR_INVERSE, %eax
+
+ movl %eax, -4(%edi)
+ movl SAVE_EDI, %edi
+ addl $STACK_SPACE, %esp
+
+ ret
+
+
+L(one):
+ shrl %cl, %eax
+ movl SAVE_ESI, %esi
+ movl SAVE_EBX, %ebx
+
+ imull VAR_INVERSE, %eax
+
+ movl SAVE_EBP, %ebp
+ movl %eax, -4(%edi)
+
+ movl SAVE_EDI, %edi
+ addl $STACK_SPACE, %esp
+
+ ret
+
+EPILOGUE()
projects / msp430-gcc.git / blobdiff