8051 Program - signed 8bit multiplication

; subroutine MUL8

; 8-Bit x 8-Bit to 16-Bit Product Signed Multiply

; 2's Complement format

;

; input: r0 = multiplicand X

; r1 = multiplier Y

;

; output: r1, r0 = product P = X x Y.

;

; calls: UMUL8, Cr0, Cr1, Mr0r1

;

; alters: acc, C, Bits 21H & 22H

MUL8:	anl PSW, #0E7H	;Register Bank 0
	acall Cr0	;2's comp -> Mag/Sign
	acall Cr1	;2's comp -> Mag/Sign
	acall UMUL8
	acall Mr0r1	;Mag/Sign -> 2's Comp
	ret

Source: Maths Subroutines for the 8051 microcontroller, W.G.Marshall 2002

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Related topics:
8051 Program - signed 16bit addition   |   8051 Program - signed 32bit addition   |   8051 Program - signed 16bit subtraction   |   8051 Program - signed 32bit subtraction   |   8051 Program - unsigned 8bit multiplication   |   8051 Program - memory subroutines   |   8051 Program - math subroutines   |   8051 Program - conversion subroutines

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List of topics: 8051

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