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58 lines
1.4 KiB
C
58 lines
1.4 KiB
C
/** @file
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64-bit Math Worker Function.
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The 32-bit versions of C compiler generate calls to library routines
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to handle 64-bit math. These functions use non-standard calling conventions.
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Copyright (c) 2009 - 2010, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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/*
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* Shifts a 64-bit unsigned value right by a certain number of bits.
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*/
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__declspec(naked) void __cdecl _aullshr (void)
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{
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_asm {
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;
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; Checking: Only handle 64bit shifting or more
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;
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cmp cl, 64
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jae _Exit
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;
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; Handle shifting between 0 and 31 bits
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;
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cmp cl, 32
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jae More32
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shrd eax, edx, cl
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shr edx, cl
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ret
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;
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; Handle shifting of 32-63 bits
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;
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More32:
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mov eax, edx
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xor edx, edx
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and cl, 31
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shr eax, cl
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ret
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;
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; Invalid number (less then 32bits), return 0
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;
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_Exit:
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xor eax, eax
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xor edx, edx
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ret
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}
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}
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