;
; David D. Clark
;
; 9 May 1987
; 11 December 1987 -- changes for DLC 3.12 (save DI and SI registers)
;

        Include macros.asm

begcode


;
; memmove -- move a block of data len bytes long from src to dest.
; The function determines whether the move should be done from
; the left or right end of the blocks.  After deciding, a jump is
; made into either moveleft() or moveright(), as appropriate, to
; actually perform word optimized moves.  A pointer to dest is
; returned.
;
; The Datalight C declaration would look like:
;
;	void *memmove(dest, src, len)
;	void *dest, *src;
;	unsigned int len;
;

		Public	memmove

func		memmove

		PUSH	BP		; save old frame pointer
		MOV	BP,SP		; set new frame pointer
		PUSH	DI		; NEW with DLC 3.12
		PUSH	SI		; "               "
		MOV	CX,P+SIZEPTR+SIZEPTR[BP]	; len
    If SPTR
		MOV	DI,P+[BP]	; ES:DI = dest
		MOV	SI,P+SIZEPTR[BP]; DS:SI = src
		MOV	AX,DI		; original dest is returned
    ELSE
		LES	DI,P+[BP]	; ES:DI = dest
		PUSH	DS		; save data segment
		LDS	SI,P+SIZEPTR[BP]; DS:SI = src
		MOV	AX,ES
		MOV	BX,DI		; AX:BX = original value of dest
    ENDIF

		CMP	SI,DI		; is src above dest?
		JAE	ml1		; move from left
		JMP	Short mr1	; move from right

memmove		EndP


;
; moveleft -- move a block of data len bytes long from src to dest
; starting at the left end.  The move is optimized to word moves
; and a (possible) single byte move.  A pointer to dest is returned.
;
; The Datalight C declaration would look like:
;
;	void *moveleft(dest, src, len)
;	void *dest, *src;
;	unsigned int len;
;

		Public	moveleft

func		moveleft

		PUSH	BP		; save old frame pointer
		MOV	BP,SP		; set new frame pointer
		PUSH	DI		; NEW with DLC 3.12
		PUSH	SI		; "               "
		MOV	CX,P+SIZEPTR+SIZEPTR[BP]	; len
    If SPTR
		MOV	DI,P+[BP]	; ES:DI = dest
		MOV	SI,P+SIZEPTR[BP]; DS:SI = src
		MOV	AX,DI		; original dest is returned
    ELSE
		LES	DI,P+[BP]	; ES:DI = dest
		PUSH	DS		; save data segment
		LDS	SI,P+SIZEPTR[BP]; DS:SI = src
		MOV	AX,ES
		MOV	BX,DI		; AX:BX = original value of dest
    ENDIF

ml1:					; alternate entry point

		CLD			; set direction forward (needed?)
		SHR	CX,1		; convert bytes to words
		JZ	mlb		; jump if no full words to move
	REP	MOVSW			; move the words
mlb:		JNC	mldone		; no bytes to move
		MOVSB			; move the left over byte
mldone:
    If LPTR
		POP	DS		; recover DS
    ENDIF
		POP	SI		; NEW with DLC 3.12
		POP	DI		; "               "
		POP	BP		; restore old frame pointer
		RET

moveleft	EndP


;
; moveright -- move a block of data len bytes long from src to dest
; starting at the right end.  The move is optimized to word moves
; and a (possible) single byte move.  A pointer to dest is returned.
;
; The Datalight C declaration would look like:
;
;	void *moveright(dest, src, len)
;	void *dest. *src;
;	unsigned int len;
;

		Public	moveright

func		moveright

		PUSH	BP		; save old frame pointer
		MOV	BP,SP		; set new frame pointer
		PUSH	DI		; NEW with DLC 3.12
		PUSH	SI		; "               "
		MOV	CX,P+SIZEPTR+SIZEPTR[BP]	; len
    If SPTR
		MOV	DI,P+[BP]	; ES:DI = dest
		MOV	SI,P+SIZEPTR[BP]; DS:SI = src
		MOV	AX,DI		; original dest is returned
    ELSE
		LES	DI,P+[BP]	; ES:DI = dest
		PUSH	DS		; save data segment
		LDS	SI,P+SIZEPTR[BP]; DS:SI = src
		MOV	AX,ES
		MOV	BX,DI		; AX:BX = original value of dest
    ENDIF

mr1:					; alternate entry point

		ADD	SI,CX		; start at high (right) end
		DEC	SI		; last source byte
		DEC	SI		; last source word
		ADD	DI,CX		; start at high (right) end
		DEC	DI		; last target byte
		DEC	DI		; last target word
		STD			; set direction backward
		SHR	CX,1		; convert bytes to words
		JZ	mrb		; jump if no full words to move
	REP	MOVSW			; move the words
mrb:		JNC	mrdone		; no bytes to move
		INC	SI		; point to source byte
		INC	DI		; point to target byte
		MOVSB			; move the left over byte

mrdone:		CLD			; reset direction flag before exit
    If LPTR
		POP	DS		; recover DS
    ENDIF
		POP	SI		; NEW with DLC 3.12
		POP	DI		; "               "
		POP	BP		; restore old frame pointer
		RET

moveright	EndP

		endcode

		End