Routines
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BC5B: compare FAC1 with (AY)
Used by the routines at B016, B1B2, BDDD and BF7B.
returns A=$00 if FAC1 = (AY). returns A=$01 if FAC1 > (AY). returns A=$FF if FAC1 < (AY)
BC5B 85 24 STA $24 save pointer low byte
This entry point is used by the routine at AD1E.
BC5D 84 25 STY $25 save pointer high byte
BC5F A0 00 LDY #$00 clear index
BC61 B1 24 LDA ($24),Y get exponent
BC63 C8 INY increment index
BC64 AA TAX copy (AY) exponent to X
BC65 F0 C4 BEQ $BC2B branch if (AY) exponent=0 and get FAC1 sign
A = $FF, Cb = 1/-ve A = $01, Cb = 0/+ve
BC67 B1 24 LDA ($24),Y get (AY) mantissa 1, with sign
BC69 45 66 EOR $66 EOR FAC1 sign (b7)
BC6B 30 C2 BMI $BC2F if signs <> do return A = $FF, Cb = 1/-ve
A = $01, Cb = 0/+ve and return
BC6D E4 61 CPX $61 compare (AY) exponent with FAC1 exponent
BC6F D0 21 BNE $BC92 branch if different
BC71 B1 24 LDA ($24),Y get (AY) mantissa 1, with sign
BC73 09 80 ORA #$80 normalise top bit
BC75 C5 62 CMP $62 compare with FAC1 mantissa 1
BC77 D0 19 BNE $BC92 branch if different
BC79 C8 INY increment index
BC7A B1 24 LDA ($24),Y get mantissa 2
BC7C C5 63 CMP $63 compare with FAC1 mantissa 2
BC7E D0 12 BNE $BC92 branch if different
BC80 C8 INY increment index
BC81 B1 24 LDA ($24),Y get mantissa 3
BC83 C5 64 CMP $64 compare with FAC1 mantissa 3
BC85 D0 0B BNE $BC92 branch if different
BC87 C8 INY increment index
BC88 A9 7F LDA #$7F set for 1/2 value rounding byte
BC8A C5 70 CMP $70 compare with FAC1 rounding byte (set carry)
BC8C B1 24 LDA ($24),Y get mantissa 4
BC8E E5 65 SBC $65 subtract FAC1 mantissa 4
BC90 F0 28 BEQ $BCBA exit if mantissa 4 equal
gets here if number <> FAC1
BC92 A5 66 LDA $66 get FAC1 sign (b7)
BC94 90 02 BCC $BC98 branch if FAC1 > (AY)
BC96 49 FF EOR #$FF else toggle FAC1 sign
BC98 4C 31 BC JMP $BC31 return A = $FF, Cb = 1/-ve A = $01, Cb = 0/+ve
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