86 lines
1.3 KiB
NASM
86 lines
1.3 KiB
NASM
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;***
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;llshr.asm - long shift right
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;
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; Copyright (c) Microsoft Corporation. All rights reserved.
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;
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;Purpose:
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; define signed long shift right routine
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; __allshr
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;
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;*******************************************************************************
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.686p
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.mmx
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.xmm
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.model flat,C
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.code
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assume ds:flat
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assume es:flat
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assume ss:flat
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assume fs:nothing
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assume gs:nothing
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include hal.inc
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;***
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;llshr - long shift right
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;
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;Purpose:
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; Does a signed Long Shift Right
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; Shifts a long right any number of bits.
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;
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;Entry:
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; EDX:EAX - long value to be shifted
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; CL - number of bits to shift by
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;
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;Exit:
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; EDX:EAX - shifted value
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;
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;Uses:
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; CL is destroyed.
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;
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;Exceptions:
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;
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;*******************************************************************************
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_allshr PROC NEAR
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;
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; Handle shifts of 64 bits or more (if shifting 64 bits or more, the result
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; depends only on the high order bit of edx).
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;
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cmp cl,64
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jae short RETSIGN
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;
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; Handle shifts of between 0 and 31 bits
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;
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cmp cl, 32
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jae short MORE32
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shrd eax,edx,cl
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sar edx,cl
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ret
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;
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; Handle shifts of between 32 and 63 bits
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;
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MORE32:
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mov eax,edx
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sar edx,31
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and cl,31
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sar eax,cl
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ret
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;
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; Return double precision 0 or -1, depending on the sign of edx
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;
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RETSIGN:
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sar edx,31
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mov eax,edx
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ret
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_allshr ENDP
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end
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