Source code of Windows XP (NT5)
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90 lines
1.6 KiB

title llshl - long shift left
;***
;llshl.asm - long shift left
;
; Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
;
;Purpose:
; define long shift left routine (signed and unsigned are same)
; __allshl
;
;Revision History:
; 11-??-83 HS initial version
; 11-30-83 DFW added medium model support
; 03-12-84 DFW broke apart; added long model support
; 06-01-84 RN modified to use cmacros
; 11-28-89 GJF Fixed copyright
; 11-19-93 SMK Modified to work on 64 bit integers
; 01-17-94 GJF Minor changes to build with NT's masm386.
; 07-08-94 GJF Faster, fatter version for NT.
; 07-13-94 GJF Further improvements from JonM.
;
;*******************************************************************************
.xlist
include cruntime.inc
include mm.inc
.list
;***
;llshl - long shift left
;
;Purpose:
; Does a Long Shift Left (signed and unsigned are identical)
; Shifts a long left any number of bits.
;
;Entry:
; EDX:EAX - long value to be shifted
; CL - number of bits to shift by
;
;Exit:
; EDX:EAX - shifted value
;
;Uses:
; CL is destroyed.
;
;Exceptions:
;
;*******************************************************************************
CODESEG
_allshl PROC NEAR
;
; Handle shifts of 64 or more bits (all get 0)
;
cmp cl, 64
jae short RETZERO
;
; Handle shifts of between 0 and 31 bits
;
cmp cl, 32
jae short MORE32
shld edx,eax,cl
shl eax,cl
ret
;
; Handle shifts of between 32 and 63 bits
;
MORE32:
mov edx,eax
xor eax,eax
and cl,31
shl edx,cl
ret
;
; return 0 in edx:eax
;
RETZERO:
xor eax,eax
xor edx,edx
ret
_allshl ENDP
end