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// *****************************************************************
//
// The Compcert verified compiler
//
// Xavier Leroy, INRIA Paris
//
// Copyright (c) 2016 Institut National de Recherche en Informatique et
// en Automatique.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of the <organization> nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT
// HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// *********************************************************************
// Helper functions for 64-bit integer arithmetic. IA32 version.
#include "sysdeps.h"
// Multiply-high signed
#define XL 12(%esp)
#define XH 16(%esp)
#define YL 20(%esp)
#define YH 24(%esp)
// Hacker's Delight section 8.3:
// - compute high 64 bits of the unsigned product X * Y (see i64_umulh.S)
// - subtract X if Y < 0
// - subtract Y if X < 0
FUNCTION(__compcert_i64_smulh)
pushl %esi
pushl %edi
movl XL, %eax
mull YL // EDX:EAX = 64-bit product XL.YL
movl %edx, %ecx
xorl %esi, %esi
xorl %edi, %edi // EDI:ESI:ECX accumulatesbits 127:32 of result
movl XH, %eax
mull YL // EDX:EAX = 64-bit product XH.YL
addl %eax, %ecx
adcl %edx, %esi
adcl $0, %edi
movl YH, %eax
mull XL // EDX:EAX = 64-bit product YH.XL
addl %eax, %ecx
adcl %edx, %esi
adcl $0, %edi
movl XH, %eax
mull YH // EDX:EAX = 64-bit product XH.YH
addl %eax, %esi
adcl %edx, %edi
// Here, EDI:ESI is the high 64 bits of the unsigned product X.Y
xorl %eax, %eax
xorl %edx, %edx
cmpl $0, XH
cmovl YL, %eax
cmovl YH, %edx // EDX:EAX = Y if X < 0, = 0 if X >= 0
subl %eax, %esi
sbbl %edx, %edi // EDI:ESI -= Y if X < 0
xorl %eax, %eax
xorl %edx, %edx
cmpl $0, YH
cmovl XL, %eax
cmovl XH, %edx // EDX:EAX = X if Y < 0, = 0 if Y >= 0
subl %eax, %esi
sbbl %edx, %edi // EDI:ESI -= X if Y < 0
// Now EDI:ESI contains the high 64 bits of the signed product X.Y
movl %esi, %eax
movl %edi, %edx
popl %edi
popl %esi
ret
ENDFUNCTION(__compcert_i64_smulh)
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