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Check Number and Convert to Integer if Float

Submitted by Steve Fewell

Routine: CheckNum&ConvFloat
Name: Check Number and Convert to Integer if Number is Floating-Point
Starting Address: &96BE
Entry criteria: The Accumulator specifies which type of value has just been processed.
Exit: If the value was Floating-Point, then the FWA's value will be converted to Integer and stored in the IWA.

Description:
Transfers the current Variable Type [stored in A] to Y in order to update the status flags.

If the current Variable Type = 0 (String) then a Type Mismatch error is given.

If the current Variable Type = positive (i.e. &40, Integer) then nothing to do as the number is already integer, so exit with the IWA's value intact.

Otherwise, the current Variable Type must be negative (i.e. &FF, Floating-Point), so the number is floating-point. So we need to convert the number into an Integer and return it in the IWA.

The Convert Float to Integer routine is used to return a Two's-complement Integer value in the FWA Mantissa (stored Most significant byte first, least significant byte last). Now, store the Integer Number in the IWA - stored the right way around (least significant byte first, and Most significant byte last), and exit.

Disassembly for the Check Number and Convert to Integer if Float routine

96BE   168 A8 TAY
96BF   240 022 F0 16 BEQ 22 --> &96D7
96C1   016 019 10 13 BPL 19 --> &96D6
96C3 B 032 066 130 20 42 82 JSR &8242   Convert Float to Integer
96C6 1 165 049 A5 31 LDA &31
96C8 - 133 045 85 2D STA &2D
96CA 2 165 050 A5 32 LDA &32
96CC , 133 044 85 2C STA &2C
96CE 3 165 051 A5 33 LDA &33
96D0 + 133 043 85 2B STA &2B
96D2 4 165 052 A5 34 LDA &34
96D4 * 133 042 85 2A STA &2A
96D6 ` 096 60 RTS
96D7 L 076 146 144 4C 92 90 JMP &9092   Type Mismatch error 6

 


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