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Length: 2560 (0xa00)
Types: TextFile
Names: »FADDSB.SRC«
└─⟦c9df7130d⟧ Bits:30005915 Pascal MT+ Release 5.2 (Jet-80)
└─ ⟦this⟧ »FADDSB.SRC«
;FLOATING POINT ADD AND SUBTRACT ROUTINES ; NAME FADDSB ENTRY FSUB,FADD,FADD1 EXT MPADD,DONE2,FPERR INCLUDE FPINIT.SRC INCLUDE FPMAC.SRC ; ; fsub -- floating point subtraction routine ; must be followed by addition routine ; fsub: setupf ;setup for 2 operands mvi a,80h ;complement sign bit xra op2+msb(x) ;of the second operand mov op2+msb(x),a ;and add since a + (-b) = a - b jr fadd1 ;jump into add routine ; ; floating point addition routine ; fadd: setupf ;setup for 2 oerands fadd1: zchk 1 ;check for a zero operand jrz copdon ;yes..copy and done zchk 2 ;check for a zero facc jz done2 ;yes...addition finished ;check range of exponents mov a,op1(x) ;get exponent of 1st op sub op2(x) ; " " " 2nd " ; ;are they equal? jrz oppos ;yes...prepare to add them mov c,a ;copy difference into c-reg jp posrlt ;otherwise make sure xra a ;that the result is +ve sub c posrlt: cpi fracln-1*8 ;is difference is too small jrc oppos ;yes..go align operands bit sign,c ;test sign of difference jz done2 ;if +ve then addition is done copdon: lxi h,op1 ;copy op1 <- op2 dad d ;point to top of op1 xchg lxi b,op2 ;point to top of op2 dad b lxi b,4 ;copy 4 bytes lddr ;op1 <- op2 jmp done2 ;and done oppos: bit sign,op1+msb(x) ;make sure args >= 0 jrz op1pos res sign,op1+msb(x) ;clear sign bit push psw ;save difference in exponents push b ;save sign of difference cmplmt 1 ;<0 , negate mantissa pop b pop psw op1pos: bit sign,op2+msb(x) jrz align res sign,op2+msb(x) ;clear sign bit push psw ;save difference in exponents push b ;save sign of difference cmplmt 2 pop b pop psw align: ana a ;are exponents equal? jrz shadd ;yes bit sign,c ;check sign of difference mov b,a ;save magnitude of difference jrz shop2 ;op1 > op2, shift op2 right ; ;op1 < op2, shift op1 right shop1: shift 1,r ;shift op1 right djnz shop1 ;until two operands line up jr shadd ;add them shop2: shift 2,r ;shift op2 right djnz shop2 shadd: shift 1,r ;shift both operands right shift 2,r ;one bit lxi h,op1+lsb ;get addr of bottom of op1 dad d xchg push h ;save base reg lxi b,op2+lsb ;get addr of bottom of op2 dad b call mpadd ;add aligned fractions pop d ;restore base reg bit sign,a ;high byte of answer is in a jz done2 cmplmt 1 ;complement fraction bset sign,op1+msb(x) ;set sign bit jmp done2 ;and done ; «eof»