diff options
Diffstat (limited to 'runtime/x86_32/i64_smulh.S')
| -rw-r--r-- | runtime/x86_32/i64_smulh.S | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/runtime/x86_32/i64_smulh.S b/runtime/x86_32/i64_smulh.S new file mode 100644 index 00000000..cc0f0167 --- /dev/null +++ b/runtime/x86_32/i64_smulh.S @@ -0,0 +1,94 @@ +// ***************************************************************** +// +// 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(__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(__i64_smulh) |