iar_short.s51

来自「8051试验程序 基础教材」· S51 代码 · 共 495 行

S51
495 行
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/*******************************************************************************
 *
 * Operations for both signed and unsigned short.
 *
 * Copyright 2003-2004 IAR Systems. All rights reserved.
 *
 * $Revision: 4427 $
 *
 ******************************************************************************/

#include "iar_common.h"

;-----------------------------------------------------------------------------
;
;	Functions: Signed short division and modulus (SDIV    AB)
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
;	Function: ?S_DIV_MOD
;
;	Description: Signed short division and modulus
;
;	Register input:
;		R1:R0  Dividend
;		R3:R2  Divisor
;
;	Register output:
;		R1:R0 = R1:R0 / R3:R2
;		R3:R2 = R1:R0 % R3:R2
;		A     = Undefined
;		B     = Undefined
;		CY    = Undefined
;
;	Stack usage: 4
;
;-----------------------------------------------------------------------------
	MODULE	?S_DIV_MOD
	RSEG	RCODE:CODE:NOROOT
        CFI BLOCK ?S_DIV_MOD USING cfi_common
        CFI NOFUNCTION	

	CFI A undefined
	CFI B undefined
	CFI R0 undefined
	CFI R1 undefined
	CFI R2 undefined
	CFI R3 undefined

	PUBLIC	?S_DIV_MOD

nn:	CLR	C
	CLR	A
	SUBB	A,R0
	MOV	R0,A
	CLR	A
	SUBB	A,R1
	MOV	R1,A
	LCALL	?US_DIV_MOD
	SJMP	NegRem
;
nx:	CLR	C
	CLR	A
	SUBB	A,R2
	MOV	R2,A
	CLR	A
	SUBB	A,R3
	MOV	R3,A
	
	MOV	A,R1
	JB	ACC.7,nn
;
	LCALL	?US_DIV_MOD

	CLR	A
	SUBB	A,R0
	MOV	R0,A
	CLR	A
	SUBB	A,R1
	MOV	R1,A
	RET

pn:	CLR	C
	CLR	A
	SUBB	A,R0
	MOV	R0,A
	CLR	A
	SUBB	A,R1
	MOV	R1,A
	LCALL	?US_DIV_MOD

	CLR	A
	SUBB	A,R0
	MOV	R0,A
	CLR	A
	SUBB	A,R1
	MOV	R1,A

	CLR	C
NegRem:	CLR	A
	SUBB	A,R2
	MOV	R2,A
	CLR	A
	SUBB	A,R3
	MOV	R3,A
	RET

?S_DIV_MOD:

	MOV	A,R3
	JB	ACC.7,nx
;
	MOV	A,R1
	JB	ACC.7,pn
	
        CFI ENDBLOCK ?S_DIV_MOD
;
; Fall through to unsigned division/modulus
;

;-----------------------------------------------------------------------------
;
;	Functions: (Un)Signed short division and modulus (SDIV    AB)
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
;	Function: ?US_DIV_MOD
;
;	Description: Unsigned short division and modulus
;
;	Register input:
;		R1:R0  Dividend
;		R3:R2  Divisor
;
;	Register output:
;		R1:R0 = R1:R0 / R3:R2
;		R3:R2 = R1:R0 % R3:R2
;		A     = Undefined
;		B     = Undefined
;		CY    = 0
;
;	Stack usage: 2
;
;-----------------------------------------------------------------------------
	RSEG	RCODE:CODE:NOROOT
	PUBLIC	?US_DIV_MOD
        CFI BLOCK ?US_DIV_MOD USING cfi_common
        CFI NOFUNCTION	

	CFI A undefined
	CFI B undefined
	CFI R0 undefined
	CFI R1 undefined
	CFI R2 undefined
	CFI R3 undefined

?US_DIV_MOD:

;=======================================;
;   Try to do a simple 8-bit division.	;
;=======================================;
	CJNE	R1,#00,t16
	CJNE	R3,#00,zero

	MOV	A,R0
	MOV	B,R2
	DIV	AB
	MOV	R0,A
	MOV	R2,B
	RET

;=======================================;
;          Divisor > dividend.		;
;=======================================;
zero:	CLR	A
	MOV	R3,A
	XCH	A,R0
	MOV	R2,A
	RET

;=======================================;
;    Try to do a 16/8-bit division.	;
;=======================================;
t16:	MOV	A,R3
	JNZ	n16

	MOV	R3,#16		; Set loop counter

Loop8:	XCH	A,R0
	RLC	A
	XCH	A,R0
	XCH	A,R1
	RLC	A
	XCH	A,R1
	RLC	A
	JNC	Just8
;
	CLR	C
	SUBB	A,R2
	CLR	C
	DJNZ	R3,Loop8
	SJMP	End8

Just8:	SUBB	A,R2
	JNC	Count8

	ADD	A,R2
Count8:	DJNZ	R3,Loop8

End8:	XCH	A,R0
	RLC	A
	CPL	A
	XCH	A,R0
	XCH	A,R1
	RLC	A
	CPL	A
	XCH	A,R1
	MOV	R2,A
	RET

;=======================================;
;          16/16-bit division.		;
;=======================================;
n16:	MOV	B,#8		; Set loop counter
	CLR	A

Loop16:	XCH	A,R0
	RLC	A
	XCH	A,R0
	XCH	A,R1
	RLC	A
	XCH	A,R1
	RLC	A
	XCH	A,R1
	SUBB	A,R2
	XCH	A,R1
	SUBB	A,R3
	JNC	Cnt16

	XCH	A,R1
	ADD	A,R2
	XCH	A,R1
	ADDC	A,R3
Cnt16:	DJNZ	B,Loop16

	MOV	R3,A
	XCH	A,R0
	RLC	A
	CPL	A
	XCH	A,R0
	CLR	A
	XCH	A,R1
	MOV	R2,A
	RET
        CFI ENDBLOCK ?US_DIV_MOD

	ENDMOD


;-----------------------------------------------------------------------------
;
;	Functions: Signed short shift right (>>)
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
;	Function: ?SS_SHR
;
;	Description: Shift a signed short object arithmetic right in IDATA
;
;	Register input:
;		R0 Points to LSB in the object
;		A  Is the number of shifts to be made
;
;	Register output:
;		A  Is zero
;		CY Is undefined
;		R0 Is not changed
;
;	Stack usage: 2
;
;-----------------------------------------------------------------------------
	MODULE	?SS_SHR
	RSEG	RCODE:CODE:NOROOT	
	PUBLIC	?SS_SHR
	PUBLIC	?SS_SHR_REW

        CFI BLOCK ?SS_SHR_REW USING cfi_common
        CFI NOFUNCTION	

	CFI R0 undefined

?SS_SHR_REW:
	JNZ	start
	DEC	R0
	RET

	CFI ENDBLOCK ?SS_SHR_REW

	RSEG	RCODE:CODE:NOROOT	
        CFI BLOCK ?SS_SHR USING cfi_common
        CFI NOFUNCTION	

	CFI R0 undefined

?SS_SHR:
	JZ	noshift

shift:
	INC	R0
	CFI ENDBLOCK ?SS_SHR
	REQUIRE	x

	RSEG	RCODE:CODE:NOROOT	
        CFI BLOCK ?SS_SHR_start USING cfi_common
        CFI NOFUNCTION	

	CFI A undefined
	CFI R0 undefined

x:
start:
	XCH	A,@R0
	MOV	C,ACC.7
	RRC	A
	XCH	A,@R0
	DEC	R0
	XCH	A,@R0
	RRC	A
	XCH	A,@R0

	DJNZ	ACC,shift

noshift:
	RET

	CFI ENDBLOCK ?SS_SHR_start
	ENDMOD


;-----------------------------------------------------------------------------
;
;	Functions: Unsigned short shift right (>>)
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
;	Function: ?US_SHR
;
;	Description: Shift a long object right in IDATA
;
;	Register input:
;		R0 Points to LSB in the object
;		A  Is the number of shifts to be made
;
;	Register output:
;		A  Is zero
;		CY Is undefined
;		R0 Is not changed
;
;	Stack usage: 2
;
;-----------------------------------------------------------------------------
	MODULE	?US_SHR		; Replaceable module
	RSEG	RCODE:CODE:NOROOT	
	PUBLIC	?US_SHR
	PUBLIC	?US_SHR_REW

        CFI BLOCK ?US_SHR_REW USING cfi_common
        CFI NOFUNCTION	

	CFI R0 undefined

?US_SHR_REW:
	JNZ	start
	DEC	R0
	RET

	CFI ENDBLOCK ?US_SHR_REW
	RSEG	RCODE:CODE:NOROOT	
        CFI BLOCK ?US_SHR USING cfi_common
        CFI NOFUNCTION	

	CFI R0 undefined

?US_SHR:
	JZ	noshift

shift:
	INC	R0

	CFI ENDBLOCK ?US_SHR
	REQUIRE	x

	RSEG	RCODE:CODE:NOROOT
        CFI BLOCK ?US_SHR_start USING cfi_common
        CFI NOFUNCTION	

	CFI A undefined
	CFI R0 undefined

x:
start:
	XCH	A,@R0
	CLR	C
	RRC	A
	XCH	A,@R0
	DEC	R0
	XCH	A,@R0
	RRC	A
	XCH	A,@R0

	DJNZ	ACC,shift

noshift:
	RET
	CFI ENDBLOCK ?US_SHR_start
	ENDMOD


;-----------------------------------------------------------------------------
;
;	Functions: (Un)signed short shift left (<<)
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
;	Function: ?S_SHL
;
;	Description: Shift a long object left in IDATA
;
;	Register input:
;		R0 Points to LSB in the object
;		A  Is the number of shifts to be made
;
;	Register output:
;		A    Is zero
;		CY   Is undefined
;		R0   Is unchanded
;
;	Stack usage: 2
;
;-----------------------------------------------------------------------------
	MODULE	?S_SHL		; Replaceable module
	RSEG	RCODE:CODE:NOROOT	
	PUBLIC	?S_SHL
	PUBLIC	?S_SHL_REW

        CFI BLOCK ?S_SHL USING cfi_common
        CFI NOFUNCTION	
	
	CFI R0 undefined

?S_SHL:
	JNZ	start
	RET

	CFI ENDBLOCK ?S_SHL

	RSEG	RCODE:CODE:NOROOT	
        CFI BLOCK ?S_SHL_REW USING cfi_common
        CFI NOFUNCTION	

	CFI R0 undefined

?S_SHL_REW:
	JZ	noshift

shift:
	DEC	R0

	CFI ENDBLOCK ?S_SHL_REW
	REQUIRE	x

	RSEG	RCODE:CODE:NOROOT	
        CFI BLOCK ?S_SHL_start USING cfi_common
        CFI NOFUNCTION	

	CFI A undefined
	CFI R0 undefined
x:
start:
	XCH	A,@R0
	CLR	C
	RLC	A
	XCH	A,@R0
	INC	R0
	XCH	A,@R0
	RLC	A
	XCH	A,@R0
	DJNZ	ACC,shift
	DEC	R0

noshift:
	RET
	CFI ENDBLOCK ?S_SHL_start
	END

iar_short.s51 - 源码说明

本页面展示了「8051试验程序 基础教材」中的 iar_short.s51 源码文件，采用 S51 编程语言编写，共 495 行代码。您可以在线阅读完整代码内容，也可以返回资源详情页下载完整源码包进行本地学习和开发。

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