116 lines
3.1 KiB
NASM
116 lines
3.1 KiB
NASM
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; int _SubUnsArrFromUnsArr(&src1,&src2,&dst,n)
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;
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; ARGUMENT
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; unsigned *src1, *src2, *dst;
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; unsigned n; /* number of ints to subtract */
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;
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; DESCRIPTION
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;
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; Subtracts src2 from scr1 giving dst. src1 and scr2 are unchanged.
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; src1, src2 and dst point to unsigned arrays.
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;
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; SIDE EFFECTS
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; dst is indeterminate on overflow. Note that although we are using
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; unsigned, we return an overflow status from here if the high-order bit
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; goes set. Caller can then determine if that is an error in his case.
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;
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; RETURNS
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; Returns GM_SUCCESS if no overflow, otherwise GM_FAILURE.
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;
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; AUTHOR
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; Andy Anderson 13-JAN-1987 13:30
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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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; aa 16-JUL-87 80-bit
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;
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;
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.SFCOND
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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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; if large memory model then:
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;
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; parm1_ = ptr to source 1
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; parm3_ = ptr to source 2;
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; parm5_ = destination segment ptr
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; parm6_ = destination offset ptr
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; parm7_ = number of unsigned's to add
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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_ = ptr to source2
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; parm3_ = ptr to destination
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; parm4_ = number of unsigned's to subtract
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;
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cproc _SubUnsArrFromUnsArr,,_sgmn
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if _LDATA
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push ds
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push es
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lds si,parm1_ ; ptr to a
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les di,parm3_ ; ptr to b
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mov cx,parm7_ ; number of uns's to subtract
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else
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mov si,parm1_
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mov di,parm2_
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mov cx,parm4_
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mov dx,parm3_ ; offset to dst
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endif
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xor bx,bx ; clear flags and offset
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sublp:
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if _LDATA
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mov ax,[si+bx] ; get a digit
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sbb ax,es:[di+bx]
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push ds ; have to exchange for large model
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push si
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lds si,parm5_ ; destination seg:offset
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mov [bx+si],ax ; mov partial product
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pop si
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pop ds
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pushf
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inc bx
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inc bx ; move to next unsigned
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loop sublp
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else
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mov ax,[si+bx] ; get a digit
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sbb ax,[di+bx]
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xchg dx,si
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mov [bx+si],ax
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xchg si,dx
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pushf
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inc bx
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inc bx ; move to next unsigned
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loop sublp
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endif
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pop bx
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test bx,0800h ; OF must be set
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jnz overf ; sense OF from last subtract
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mov ax,GM_SUCCESS ; set SUCCESS return for caller
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exit:
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if _LDATA
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mov cx,parm7_
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else
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mov cx,parm4_
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endif
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dec cx ; since we've already poped one off
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sal cx,1 ; the stack, make byte offset -2
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add sp,cx ; clean up stack from pushf's
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if _LDATA
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pop es
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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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