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[/] [zipcpu/] [trunk/] [sw/] [lib/] [divs.S] - Diff between revs 59 and 69

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Rev 59 Rev 69
Line 12... Line 12...
;       + -     (x= 22,y=-4,R0=-5,R1= 2)
;       + -     (x= 22,y=-4,R0=-5,R1= 2)
;       - -     (x=-22,y=-4,R0= 5,R1=-2)
;       - -     (x=-22,y=-4,R0= 5,R1=-2)
;
;
;
;
;
;
divs:   ; Given R0,R1, computer R0 = R0/R1 and R1 = R0%R1 for signed R0,R1
lib_divs: ; Given R0,R1, computer R0 = R0/R1 and R1 = R0%R1 for signed R0,R1
        SUB     2,SP
        SUB     2,SP
        ; (stall)
        STO     R2,(SP)
        STO     R3,2(SP)
        STO     R3,2(SP)
        ;
        ;
        CLR     R3              ; Keep track of resulting sign in R2
        CLR     R3              ; Keep track of resulting sign in R2
        TST     -1,R0           ; Is R0 negative?
        TST     -1,R0           ; Is R0 negative?
        MOV     ret_div32s(PC),R2
        MOV     ret_div32s(PC),R2
Line 27... Line 27...
        MOV.LT  divu_divs_return(PC),R2
        MOV.LT  divu_divs_return(PC),R2
        TST     -1,R1           ; Is R1 negative?
        TST     -1,R1           ; Is R1 negative?
        XOR.LT  1,R3            ; If so, result will be opposite sign of before
        XOR.LT  1,R3            ; If so, result will be opposite sign of before
        NEG.LT  R1              ; Now we get R1=ABS(R1)
        NEG.LT  R1              ; Now we get R1=ABS(R1)
        MOV.LT  divu_divs_return(PC),R2
        MOV.LT  divu_divs_return(PC),R2
        STO     R2,1(SP)
        BRA     lib_divu        ; Do our unsigned multiply
        BRA     divu            ; Do our unsigned multiply
 
        ; JSR   divu            ; Do our unsigned multiply
        ; JSR   divu            ; Do our unsigned multiply
divu_divs_return:
divu_divs_return:
        TST     1,R3            ; Check resulting sign
        TST     1,R3            ; Check resulting sign
        NEG.NE  R0              ; Need to flip the sign of our result
        NEG.NE  R0              ; Need to flip the sign of our result
        TST     2,R3            ; Now, if R1 was originally negative
        TST     2,R3            ; Now, if R1 was originally negative
        NEG.NE  R1              ; Then negate R1
        NEG.NE  R1              ; Then negate R1
ret_div32s:
ret_div32s:
 
        LOD     (SP),R2
        LOD     2(SP),R3
        LOD     2(SP),R3
        LOD     3(SP),R2
 
        ADD     2,SP
        ADD     2,SP
        JMP     R2
        JMP     R2
 
 

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