Routines
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E000: start of the kernal ROM
Used by the routine at BFED.
EXP() continued
E000 85 56 STA $56 save FAC2 rounding byte
E002 20 0F BC JSR $BC0F copy FAC1 to FAC2
E005 A5 61 LDA $61 get FAC1 exponent
E007 C9 88 CMP #$88 compare with EXP limit (256d)
E009 90 03 BCC $E00E branch if less
E00B 20 D4 BA JSR $BAD4 handle overflow and underflow
E00E 20 CC BC JSR $BCCC perform INT()
E011 A5 07 LDA $07 get mantissa 4 from INT()
E013 18 CLC clear carry for add
E014 69 81 ADC #$81 normalise +1
E016 F0 F3 BEQ $E00B if $00 result has overflowed so go handle it
E018 38 SEC set carry for subtract
E019 E9 01 SBC #$01 exponent now correct
E01B 48 PHA save FAC2 exponent
swap FAC1 and FAC2
E01C A2 05 LDX #$05 4 bytes to do
E01E B5 69 LDA $69,X get FAC2,X
E020 B4 61 LDY $61,X get FAC1,X
E022 95 61 STA $61,X save FAC1,X
E024 94 69 STY $69,X save FAC2,X
E026 CA DEX decrement count/index
E027 10 F5 BPL $E01E loop if not all done
E029 A5 56 LDA $56 get FAC2 rounding byte
E02B 85 70 STA $70 save as FAC1 rounding byte
E02D 20 53 B8 JSR $B853 perform subtraction, FAC2 from FAC1
E030 20 B4 BF JSR $BFB4 do - FAC1
E033 A9 C4 LDA #$C4 set counter pointer low byte
E035 A0 BF LDY #$BF set counter pointer high byte
E037 20 59 E0 JSR $E059 go do series evaluation
E03A A9 00 LDA #$00 clear A
E03C 85 6F STA $6F clear sign compare (FAC1 EOR FAC2)
E03E 68 PLA get saved FAC2 exponent
E03F 20 B9 BA JSR $BAB9 test and adjust accumulators
E042 60 RTS
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