Routines
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BF7B: perform power function
BF7B F0 70 BEQ $BFED perform EXP()
BF7D A5 69 LDA $69 get FAC2 exponent
BF7F D0 03 BNE $BF84 branch if FAC2<>0
BF81 4C F9 B8 JMP $B8F9 clear FAC1 exponent and sign and return
BF84 A2 4E LDX #$4E set destination pointer low byte
BF86 A0 00 LDY #$00 set destination pointer high byte
BF88 20 D4 BB JSR $BBD4 pack FAC1 into (XY)
BF8B A5 6E LDA $6E get FAC2 sign (b7)
BF8D 10 0F BPL $BF9E branch if FAC2>0
else FAC2 is -ve and can only be raised to an integer power which gives an x + j0 result
BF8F 20 CC BC JSR $BCCC perform INT()
BF92 A9 4E LDA #$4E set source pointer low byte
BF94 A0 00 LDY #$00 set source pointer high byte
BF96 20 5B BC JSR $BC5B compare FAC1 with (AY)
BF99 D0 03 BNE $BF9E branch if FAC1 <> (AY) to allow Function Call error. this will leave FAC1 -ve and cause a Function Call error when LOG() is called
BF9B 98 TYA clear sign b7
BF9C A4 07 LDY $07 get FAC1 mantissa 4 from INT() function as sign in Y for possible later negation, b0 only needed
BF9E 20 FE BB JSR $BBFE save FAC1 sign and copy ABS(FAC2) to FAC1
BFA1 98 TYA copy sign back ..
BFA2 48 PHA .. and save it
BFA3 20 EA B9 JSR $B9EA perform LOG()
BFA6 A9 4E LDA #$4E set pointer low byte
BFA8 A0 00 LDY #$00 set pointer high byte
BFAA 20 28 BA JSR $BA28 do convert AY, FCA1*(AY)
BFAD 20 ED BF JSR $BFED perform EXP()
BFB0 68 PLA pull sign from stack
BFB1 4A LSR A b0 is to be tested
BFB2 90 0A BCC $BFBE if no bit then exit
This entry point is used by the routines at BD67, E000, E26B and E30E.
do - FAC1
BFB4 A5 61 LDA $61 get FAC1 exponent
BFB6 F0 06 BEQ $BFBE exit if FAC1_e = $00
BFB8 A5 66 LDA $66 get FAC1 sign (b7)
BFBA 49 FF EOR #$FF complement it
BFBC 85 66 STA $66 save FAC1 sign (b7)
BFBE 60 RTS
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