ReC98/libs/BorlandC/H_LRSH.ASM

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2014-08-14 17:49:23 +00:00
; *Not* the original file, but an edit to turn it into an includable slice.
; Changes include:
; * removal of RULES.ASI to eliminate redundancy
; * removal of the 'CODE' segment declaration (for obvious reasons)
;[]-----------------------------------------------------------------[]
;| H_LRSH.ASM -- long shift right |
;[]-----------------------------------------------------------------[]
;
; C/C++ Run Time Library - Version 5.0
;
; Copyright (c) 1987, 1992 by Borland International
; All Rights Reserved.
;
public LXRSH@
public F_LXRSH@
public N_LXRSH@
N_LXRSH@:
pop bx ;fix up for far return
push cs
push bx
LXRSH@:
F_LXRSH@:
cmp cl,16
jae lrsh_@small
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mov bx,dx ; save the high bits
shr ax,cl ; now shift each half
sar dx,cl
;
; We now have a hole in AX where the lower bits of
; DX should have been shifted. So we must take our
; copy of DX and do a reverse shift to get the proper
; bits to be or'ed into AX.
;
neg cl
add cl,16
shl bx,cl
or ax,bx
retf
lrsh_@small:
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sub cl,16 ; for shifts more than 15, do this
; short sequence.
xchg ax,dx ;
cwd ; We have now done a shift by 16.
sar ax,cl ; Now shift the remainder.
retf