Routines
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B8FE: add FAC2 mantissa to FAC1 mantissa
Used by the routine at B86A.
B8FE 65 56 ADC $56 add FAC2 rounding byte
B900 85 70 STA $70 save FAC1 rounding byte
B902 A5 65 LDA $65 get FAC1 mantissa 4
B904 65 6D ADC $6D add FAC2 mantissa 4
B906 85 65 STA $65 save FAC1 mantissa 4
B908 A5 64 LDA $64 get FAC1 mantissa 3
B90A 65 6C ADC $6C add FAC2 mantissa 3
B90C 85 64 STA $64 save FAC1 mantissa 3
B90E A5 63 LDA $63 get FAC1 mantissa 2
B910 65 6B ADC $6B add FAC2 mantissa 2
B912 85 63 STA $63 save FAC1 mantissa 2
B914 A5 62 LDA $62 get FAC1 mantissa 1
B916 65 6A ADC $6A add FAC2 mantissa 1
B918 85 62 STA $62 save FAC1 mantissa 1
B91A 4C 36 B9 JMP $B936 test and normalise FAC1 for C=0/1
B91D 69 01 ADC #$01 add 1 to exponent offset
B91F 06 70 ASL $70 shift FAC1 rounding byte
B921 26 65 ROL $65 shift FAC1 mantissa 4
B923 26 64 ROL $64 shift FAC1 mantissa 3
B925 26 63 ROL $63 shift FAC1 mantissa 2
B927 26 62 ROL $62 shift FAC1 mantissa 1
This entry point is used by the routine at B8D7.
normalise FAC1
B929 10 F2 BPL $B91D loop if not normalised
B92B 38 SEC set carry for subtract
B92C E5 61 SBC $61 subtract FAC1 exponent
B92E B0 C7 BCS $B8F7 branch if underflow (set result = $0)
B930 49 FF EOR #$FF complement exponent
B932 69 01 ADC #$01 +1 (twos complement)
B934 85 61 STA $61 save FAC1 exponent
test and normalise FAC1 for C=0/1
B936 90 0E BCC $B946 exit if no overflow
This entry point is used by the routine at BC1B.
normalise FAC1 for C=1
B938 E6 61 INC $61 increment FAC1 exponent
B93A F0 42 BEQ $B97E if zero do overflow error then warm start
B93C 66 62 ROR $62 shift FAC1 mantissa 1
B93E 66 63 ROR $63 shift FAC1 mantissa 2
B940 66 64 ROR $64 shift FAC1 mantissa 3
B942 66 65 ROR $65 shift FAC1 mantissa 4
B944 66 70 ROR $70 shift FAC1 rounding byte
B946 60 RTS
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