.titl PDMl ;DoubleAdd(a,b) -- a,b pointers to double-precision numbers ;DoubleAddV(a,i) -- a = a+i; where 'i' is a single-precision value ;DoubleSub(a,b) -- a-b ;DoubleShr(a) -- shift a right (arithmetically) by one bit ;DoubleCop(a,b) -- a_b ;MulDiv(a,b,c) returns (unsigned) a*b/c without losing intermediate precision ;MulDivT(a,b,c) returns (unsigned) a*b/c , without rounding ;MulMod(a,b,c) returns (unsigned) (a*b) rem c ;MulFull(a,b,v) v!0 and v!1 stuffed with (signed) double result a*b ;DivFull(a,b) -- returns (signed) a/b; where 'a' is a double-precision value ;Ugt(a,b) returns true if a>b unsigned 16-bit ;TGr(a,b) returns true if a>b using "true compare" ;BitBLT(table) -- calls BITBLT savedPC=1 temp=2 extraArguments=3 SWAT=401 ;should be 77400 for real SWAT call .srel DoubleAdd: .DoubleAdd DoubleSub: .DoubleSub DoubleShr: .DoubleShr DoubleCop: .DoubleCop MulDiv: .UMulDiv MulDivT: .UMulDivT MulMod: .MulMod MulFull: .MulFull DivFull: .DivFull DoubleAddV: .DoubleAddImmediate Ugt: .Ugt TGr: .TGr BitBLT: .BitBLT .ent DoubleAdd,DoubleSub,DoubleShr,DoubleCop,MulDiv,MulDivT,MulMod,MulFull,DoubleAddV,DivFull,Ugt,TGr,BitBLT .nrel 0 .BitBLT: sta 3 savedPC,2 sta 2,saved2 mov 0,2 sub 1,1 ;AC1_0 BITBLT lda 2,saved2 lda 3 savedPC,2 jmp 1,3 .DoubleAdd: sta 3 savedPC,2 sta 1 temp,2 ; => first word of arg 2 mov 1,3 lda 1,1,3 ; word 2 of arg 2 mov 0 3 lda 0,1,3 ; word 2 of arg 1 addz 1,0 sta 0,1,3 ; word 2 of arg 1 lda 0,0,3 ; word 1 of arg 1 lda 1 @temp,2 ; word 1 of arg 2 mov 0,0,szc inc 0,0 add 1,0 sta 0,0,3 ; word 1 of arg 1 lda 3 savedPC,2 jmp 1,3 .DoubleAddImmediate: sta 3 savedPC,2 sta 2,saved2 mov 0 3 ; save arg 1 movl# 1 1,snc ; generate high order word of i sub 2 2,skp ; 0 if positive adc 2 2 ; -1 if negative lda 0 1 3 ; word 2 of arg 1 addz 1 0 szc ; add integer inc 2,2 ; add in carry sta 0 1 3 ; replace word 2 of arg 1 lda 0 0 3 ; word 1 of arg 1 add 2 0 ; result to ac0 sta 0 0 3 ; store result lda 2,saved2 lda 3 savedPC,2 jmp 1 3 saved2: 0 .DoubleSub: sta 3 savedPC,2 sta 1 temp,2 ; => first word of arg 2 mov 1 3 lda 1,1,3 ; word 2 of arg 2 mov 0 3 lda 0,1,3 ; word 2 of arg 1 subz 1,0 sta 0,1,3 ; word 2 of arg 1 lda 0,0,3 ; word 1 of arg 1 lda 1 @temp,2 ; word 1 of arg 2 mov 0,0,szc inc 0,0 adc 1,0 sta 0,0,3 ; word 1 of arg 1 lda 3 savedPC,2 jmp 1,3 .DoubleShr: sta 3 savedPC,2 MOV 0,3 ;SAVE POINTER TO NUMBER LDA 0,0,3 ;HIGH ORDER PART MOVL# 0,0,SZC ;TEST SIGN BIT MOVOR 0,0,SKP ;SHIFT IN A 1 MOVZR 0,0 ;SHIFT IN A 0 STA 0,0,3 LDA 1,1,3 ;LOW ORDER MOVR 1,1 ;SHIFT CARRY BIT IN STA 1,1,3 ;AND REPLACE lda 3 savedPC,2 jmp 1,3 ;RETURN INTEGER PART... .DoubleCop: sta 3 savedPC,2 mov 0 3 ; destination address sta 1 temp,2 lda 0 @temp,2 ; high order sta 0 0,3 ; save it isz temp,2 lda 0 @temp,2 sta 0 1,3 ; low order lda 3 savedPC,2 jmp 1,3 ;RETURN INTEGER PART... .UMulDiv: sta 3 savedPC,2 mov 2,3 ; stack pointer mov 0 2 ; a lda 0 extraArguments,3 ; c movzr 0 0 ; c/2 for rounding mul ; go multiply lda 2 extraArguments,3 ; c div mov# 0,0 mov 1 0 ; answer mov 3 2 lda 3 savedPC,2 jmp 1,3 .UMulDivT: sta 3 savedPC,2 mov 2,3 ; stack pointer mov 0 2 ; a sub 0 0 mul ; go multiply lda 2 extraArguments,3 ; c div mov# 0,0 mov 1 0 ; answer mov 3 2 lda 3 savedPC,2 jmp 1,3 .MulMod: sta 3 savedPC,2 mov 2,3 ; stack pointer mov 0 2 ; a sub 0 0 mul ; go multiply lda 2 extraArguments,3 ; c div mov# 0,0 mov 3 2 ;div returns remainder in AC0 lda 3 savedPC,2 jmp 1,3 .MulFull: ;this routine uses the following trick. In two's complement notation, -k ; is represented as 2^16 - k. Thus, for example, an unsigned multiply ; of (2^16 - k)*(2^16 - m) would yield 2^32 - (k + m)*2^16 + k*m. ; This routine calculates the correction factor k + m and adds it to the ; high order word of the product. Similarly if only one operand is negative. sta 3 savedPC,2 mov 2 3 ; stack pointer mov 0 2 ; a movl# 1,1,snc ; leave a as correction factor if b is negative sub 0,0 ; otherwise zero correction factor movl# 2,2,szc ; if a is negative ... add 1,0 ; ... add b to the correction factor sta 0,temp,3 ; finally save correction sub 0,0 ; and clear 0 for multiplication mul lda 2,temp,3 ;pick up correction factor sub 2,0 ; subtract it from high order word lda 2,extraArguments,3 sta 0,0,2 ;give high order to user sta 1,1,2 ; and low order mov 3,2 lda 3,savedPC,2 jmp 1,3 .DivFull: sta 3 savedPC,2 mov 2 3 ; stack pointer sta 1,temp,3 ; stash divisor for now movz 0,2 ; => dividend (and clear carry) lda 0,0,2 ; high order dividend lda 1,1,2 ; low order dividend lda 2,temp,3 ; divisor again movl# 0,0,snc ; skip if dividend is negative jmp .+5 ; don't bother with next if positive neg 1,1,szr ; negate double word dividend com 0,0,skp neg 0,0 negz 2,2 ; also negate divisor (leave carry clear) movl# 2,2,szc ; is divisor negative? nego 2,2 ; if so, negate it and set carry div ; div preserves carry SWAT ; SWAT mov 1,0,szc ; answer and if carry was set ... neg 0,0 ; ... negate it mov 3 2 lda 3 savedPC,2 jmp 1 3 .Ugt: sgtu 0,1 mkzero 0,0,skp mkminusone 0,0 jmp 1,3 .TGr: sta 3 savedPC,2 subzr 3,3 and 1,3 addl 0,3 adc# 1,0,snc sub 0,0,skp ; false adc 0,0 ; true lda 3 savedPC,2 jmp 1,3 .END