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;==================================================================
; 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
;==================================================================; subroutine UMUL8; 8-Bit x 8-Bit to 16-Bit Product Unsigned Multiply;; input: r0 = multiplicand X; r1 = multiplier Y;; output: r1, r0 = product P = X x Y.;; alters: acc;==================================================================
UMUL8: push b mov a, r0 ; read X and ... mov b, r1 ; ... Y mul ab ; multiply X and Y mov r1, b ; save result high ... mov r0, a ; ... and low pop b ret
;====================================================================; subroutine MUL816; 8-Bit x 16-Bit to 32-Bit Product signed Multiply; 2's Complement format ;; input: r0 = multiplicand X; r3, r2 = multiplier Y;; output: r3, r2, r1, r0 = product P = X x Y (r3 = sign extension) ;; calls: Cr0, Cr2r3, Mr0r3 ;; alters: acc, C, Bits 21H & 22H;====================================================================
MUL816: push b anl PSW, #0E7H ; Register Bank 0 acall Cr0 ; 2's comp -> Mag/Sign acall Cr2r3 ; 2's comp -> Mag/Sign mov a, r0 ; load X low byte into acc mov b, r2 ; load Y low byte into B mul ab ; multiply push acc ; stack result low byte push b ; stack result high byte mov a, r0 ; load X into acc again mov b, r3 ; load Y high byte into B mul ab ; multiply pop 00H ; recall X*YL high byte add a, r0 ; add X*YL high and X*YH low mov r1, a ; save result clr a ; clear accumulator addc a, b ; a = b + carry flag mov r2, a ; save result pop 00H ; get low result mov r3, #0 acall Mr0r3 ; Mag/Sign -> 2's Comp pop b ret
;====================================================================; subroutine MUL16; 16-Bit x 16-Bit to 32-Bit Product Signed Multiply; 2's Complement format;; input: r1, r0 = multiplicand X; r3, r2 = multiplier Y;; output: r3, r2, r1, r0 = product P = X x Y;; calls: UMUL16, Cr0r1, Cr2r3, Mr0r3;; alters: acc, C, Bits 21H & 22H;====================================================================
MUL16: anl PSW, #0E7H ; Register Bank 0 acall Cr0r1 ; 2's comp -> Mag/Sign acall Cr2r3 ; 2's comp -> Mag/Sign acall UMUL16 acall Mr0r3 ; Mag/Sign -> 2's Comp ret
;====================================================================; subroutine UMUL16; 16-Bit x 16-Bit to 32-Bit Product Unsigned Multiply;; input: r1, r0 = multiplicand X; r3, r2 = multiplier Y;; output: r3, r2, r1, r0 = product P = X x Y;; alters: acc, C;====================================================================
UMUL16: push B push dpl mov a, r0 mov b, r2 mul ab ; multiply XL x YL push acc ; stack result low byte push b ; stack result high byte mov a, r0 mov b, r3 mul ab ; multiply XL x YH pop 00H add a, r0 mov r0, a clr a addc a, b mov dpl, a mov a, r2 mov b, r1 mul ab ; multiply XH x YL add a, r0 mov r0, a mov a, dpl addc a, b mov dpl, a clr a addc a, #0 push acc ; save intermediate carry mov a, r3 mov b, r1 mul ab ; multiply XH x YH add a, dpl mov r2, a pop acc ; retrieve carry addc a, b mov r3, a mov r1, 00H pop 00H ; retrieve result low byte pop dpl pop B ret
;================================================================= ; subroutine Cr0 ; 8-Bit 2's Complement -> magnitude / Sign Bit Conversion ; input: r0 = signed byte ; output: r0 = magnitude ; Bit 21H = sign (21H is set if r0 is a negative number) ; alters: acc ;=================================================================
Cr0: mov a, r0 ; read X into accumulator jb acc.7, Cr0a ; X is negative if bit 7 is 1 clr 21H ; clear sign bit if 'positive' ret ; done
Cr0a: cpl a ; X negative, find abs value inc a ; XA = complement(XT)+1 mov r0, a ; save magnitude setb 21H ; set sign bit if 'negative' ret
;=================================================================; subroutine Cr1; 8-Bit 2's Complement -> magnitude / Sign Bit Conversion ;; input: r1 = signed byte;; output: r1 = magnitude; Bit 22H = sign (22H is set if r1 is a negative number);; alters: acc;=================================================================
Cr1: mov a, r1 ; read X into accumulator jb acc.7, Cr1a ; X is negative if bit 7 is 1 clr 22H ; clear sign bit if 'positive' ret ; done
Cr1a: cpl a ; X negative, find abs value inc a ; XA = complement(XT)+1 mov r1, a ; save magnitude setb 22H ; set sign bit if 'negative' ret;=================================================================== ; subroutine Cr0r1 ; 16-Bit 2's Complement -> magnitude / Sign Bit Conversion ; ; input: r1, r0 = signed word ; ; output: r1, r0 = magnitude ; Bit 21H = sign (21H is set if negative number) ; ; alters: acc, C;===================================================================
Cr0r1: mov a, r1 ; high byte into accumulator jb acc.7, c0a ; negative if bit 7 is 1 clr 21H ; clear sign bit if 'positive' ret ; done
c0a: setb 21H ; set sign flag mov a, r0 ; number is negative cpl a ; complement add a, #1 ; and add +1 mov r0, a mov a, r1 ; get next byte cpl a ; complement addc a, #0 mov r1, a ret;==================================================================== ; subroutine Cr2r3 ; 16-Bit 2's Complement -> magnitude / Sign Bit Conversion ; ; input: r3, r2 = signed word ; ; output: r3, r2 = magnitude ; Bit 22H = sign (22H is set if negative number) ; ; alters: acc, C;====================================================================
Cr2r3: mov a, r3 ; read high into accumulator jb acc.7, c1a ; negative if bit 7 is 1 clr 22H ; clear sign bit if 'positive' ret ; done
c1a: setb 22H ; set sign flag mov a, r2 ; number is negative cpl a ; complement add a, #1 ; and add +1 mov r2, a mov a, r3 ; get next byte cpl a ; complement addc a, #0 mov r3, a ret
;==================================================================== ; subroutine Cr4r5 ; 16-Bit 2's Complement -> magnitude / Sign Bit Conversion ; ; input: r5, r4 = signed word ; ; output: r5, r4 = magnitude ; Bit 22H = sign (22H is set if negative number) ; ; alters: acc, C;====================================================================
Cr4r5: mov a, r5 ; read high into accumulator jb acc.7, c3a ; negative if bit 7 is 1 clr 22H ; clear sign bit if 'positive' ret ; done
c3a: setb 22H ; set sign flag mov a, r4 ; number is negative cpl a ; complement add a, #1 ; and add +1 mov r4, a mov a, r5 ; get next byte cpl a ; complement addc a, #0 mov r5, a ret
;==================================================================== ; subroutine Cr0r3 ; 32-Bit 2's Complement -> magnitude / Sign Bit Conversion ; ; input: r3, r2, r1, r0 = signed word ; ; output: r3, r2, r1, r0 = magnitude ; Bit 21H = sign (21H is set if negative number) ; ; alters: acc;====================================================================
Cr0r3: mov a, r3 ; read high into accumulator jb acc.7, c2a ; negative if bit 7 is 1 clr 21H ; clear sign flag if 'positive' ret ; done
c2a: setb 21H ; set sign flag mov a, r0 ; number is negative cpl a ; complement add a, #1 ; and add +1 mov r0, a mov a, r1 ; get next byte cpl a ; complement addc a, #0 mov r1,a mov a, r2 ; get next byte cpl a ; complement addc a, #0 mov r2,a mov a, r3 ; get next byte cpl a ; complement addc a, #0 mov r3, a ret ; done
;================================================================== ; subroutine Mr0 ; 8-Bit magnitude / Sign Bit -> 2's Complement Conversion ; ; input: r0 = magnitude ; Bits 21H & 22H = sign bits of operands X and Y ; (set if negative) ; ; output: r0 = signed byte ; ; alters: acc;==================================================================
Mr0: jb 21H, Mr0b ; test X sign jb 22H, Mr0a ; test Y sign ret
Mr0b: jnb 22H, Mr0a ret
Mr0a: mov a, r0 ; if r0 negative, get abs value cpl a ; complement magnitude of X inc a ; r0 = complement(r0)+1 mov r0, a ; save in 2's complement ret ; done
;==================================================================== ; subroutine Mr0r1 ; 16-Bit magnitude / Sign Bit -> 2's Complement Conversion ; ; input: r1, r0 = magnitude ; Bits 21H & 22H = sign bits of operands X and Y ; (set if negative) ; ; output: r1, r0 = signed word ; ; alters: acc, C;====================================================================
Mr0r1: jb 21H, Mr0r1b ; test X sign jb 22H, Mr0r1a ; test Y sign ret
Mr0r1b: jnb 22H, Mr0r1a ret
Mr0r1a: mov a, r0 ; negate number cpl a ; complement add a, #1 ; and add +1 mov r0, a mov a, r1 ; get next byte cpl a ; complement addc a, #0 mov r1, a ret
;==================================================================== ; subroutine Mr0r3 ; 32-Bit magnitude / Sign Bit -> 2's Complement Conversion ; ; input: r3, r2, r1, r0 = magnitude ; Bits 21H & 22H = sign bits of operands X and Y ; (set if negative) ; ; output: r3, r2, r1, r0 = signed word ; ; alters: acc, C;====================================================================
Mr0r3: jb 21H, Mr0r3b ; test X sign jb 22H, Mr0r3a ; test Y sign ret
Mr0r3b: jnb 22H, Mr0r3a ret
Mr0r3a: mov a, r0 ; negate number cpl a ; complement add a, #1 ; and add +1 mov r0, a mov a, r1 ; get next byte cpl a ; complement addc a, #0 mov r1, a mov a, r2 ; get next byte cpl a ; complement addc a, #0 mov r2, a mov a, r3 ; get next byte cpl a ; complement addc a, #0 mov r3, a ret ; done