75 lines
1.7 KiB
NASM
75 lines
1.7 KiB
NASM
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; int _DoubleUnsArr(a,n)
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;
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; ARGUMENT
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; unsigned *a[];
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; unsigned n;
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;
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; DESCRIPTION
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; Doubles the number a (taken as one number of 'n' 16-bit unsigned's).
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;
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; SIDE EFFECTS
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; Overflow if sign bit goes set in high-order unsigned
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;
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; RETURNS
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; None, athough they are set in AX for future use if needed
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;
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; AUTHOR
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; Andy Anderson 31-JAN-1987 14:45
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; Copyright (C) 1987-90 Greenleaf Software Inc. All Rights Reserved.
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;
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; MODIFICATIONS
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;
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;
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;
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include model.h
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include prologue.h
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include gm.equ
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pseg gmath
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;
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;
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; if large memory model then:
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;
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; parm1_ = ptr to source 1
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; parm3_ = number of words to shift left (multipy by 2)
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;
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; for if small model then
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; parm1_ = ptr to source1
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; parm2_ = number of words to shift left (multipy by 2)
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;
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;
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cproc _DoubleUnsArr,,_dmi
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if _LDATA
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push ds
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lds si,parm1_ ; ptr to a
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mov cx,parm3_ ; get number of words to shift
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else
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mov si,parm1_
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mov cx,parm2_ ; ditto for small model
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endif
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xor ax,ax ; clear flags
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lp:
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rcl Word Ptr [si],1 ; word and multipy it by 2
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inc si ; and increase the index (offset)
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inc si ; without disturbing the carry
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loop lp ; for next until done
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jc overf ; carry-out is overflow and
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test [si-2],8000h ; overflow if high-order set
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jnz overf
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mov ax,GM_SUCCESS ; otherwise no overflow
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exit:
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if _LDATA
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pop ds
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endif
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cproce
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overf:
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mov ax,GM_FAILURE
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jmp short exit
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endps
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END
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