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**Submitted by Steve Fewell**

**Starting Address**: &9C82 (or &9C65 to convert Integer first)

**Entry criteria**: FWA contains the value to compare.

BASIC Text pointer points to the expression to compare FWA with.

**Exit**: Zero flag = 1 if values are equal. Carry is set if value 1 > value 2; clear otherwise.

Y = 00.

**Description**:

**9C65 Convert Integer to Float and initialise Float values:**

This routine is called during Compare Integer values if the second value in the

compare is a Float value (not an Integer value, as expected).

Pop the IWA value from the processor stack (the first value to compare).

Push the FWA value (second value to compare) to the BASIC Stack.

Convert the IWA (first value to compare) to a Float value.

Copy this result from the FWA to the FWB.

Pop the Float from the BASIC Stack (second value to compare) and unpack the returned

variable (pointed to by &4A, &4B) to the FWA.

Now, FWA = second value to compare & FWB = first value to compare. Go to &9C92 to perform

the compare.

**9C82 Initialise and get the Float values:**

Push FWA to stack (first value to compare).

Gosub &9E4C to get the result of the expression (in the BASIC program text line),

[we need to process expression level (+,-) upwards as any operators below this level should

only be evaluated once this compare has been evaluated].

Copy A to Y [to update processor flags] and call &96DD to check that the result obtained

is a Float value - if it is an Integer it will be converted to Float. If it is a String then a

Type Mismatch error will be generated.

Pop the Float variable from the stack and unpack this variable to the FWB.

Now, the FWB = the first value to compare, and the FWA = second value to compare.

**9C92 Compare the Float values:**

Y = #&00

Reset bottom 7 bits of the FWB sign byte.

Load the FWA sign bit & reset the bottom 7 bits of the loaded value, then compare

this sign with the FWB sign byte. If the signs are not equal then exit (with C=1 if FWA>FWB).

Compare the FWB exponent with the FWA exponent (if not equal then stop as we have result).

Compare the FWB Mantissa byte 1 with the FWA Mantissa byte 1 (if not equal then stop as we have result).

Compare the FWB Mantissa byte 2 with the FWA Mantissa byte 2 (if not equal then stop as we have result).

Compare the FWB Mantissa byte 3 with the FWA Mantissa byte 3 (if not equal then stop as we have result).

Compare the FWB Mantissa byte 4 with the FWA Mantissa byte 4 (if not equal then stop as we have result).

If the Mantissa and exponents are equal, then the values are equal, so exit with A = 0.

Otherwise, C = 1 (if FWA > FWB). However, if both values are negative (Sign byte is 1), then

we need to reverse the carry, so that C = 0 (if it was 1), or C = 1 (if it was zero)

this is because the value that was higher is actually lower (as it is negative).

Exit with A = &01 (as values not equal).

9C65 | h | 104 | 68 | PLA |

9C66 | * | 133 042 | 85 2A | STA &2A |

9C68 | h | 104 | 68 | PLA |

9C69 | + | 133 043 | 85 2B | STA &2B |

9C6B | h | 104 | 68 | PLA |

9C6C | , | 133 044 | 85 2C | STA &2C |

9C6E | h | 104 | 68 | PLA |

9C6F | - | 133 045 | 85 2D | STA &2D |

9C71 | 032 250 187 | 20 FA BB | JSR &BBFA Push FWA to Stack | |

9C74 | 032 133 129 | 20 85 81 | JSR &8185 Convert Integer to Float | |

9C77 | 032 011 164 | 20 0B A4 | JSR &A40B Copy FWA to FWB | |

9C7A | 032 232 187 | 20 E8 BB | JSR &BBE8 Pop Float from Stack | |

9C7D | A | 032 065 165 | 20 41 A5 | JSR &A541 Unpack Float variable to FWA |

9C80 | 128 016 | 80 10 | BRA 16 --> &9C92 | |

9C82 | 032 250 187 | 20 FA BB | JSR &BBFA Push FWA to Stack | |

9C85 | L | 032 076 158 | 20 4C 9E | JSR &9E4C Expression Handler (+, - level onwards) |

9C88 | 168 | A8 | TAY | |

9C89 | 032 221 150 | 20 DD 96 | JSR &96DD Check Float value (conv int to float, etc.) | |

9C8C | 032 232 187 | 20 E8 BB | JSR &BBE8 Pop Float from Stack (to &4A, &4B) | |

9C8F | 032 224 164 | 20 E0 A4 | JSR &A4E0 Unpack Float variable to FWB | |

9C92 | 160 000 | A0 00 | LDY#&00 | |

9C94 | 169 127 | A9 7F | LDA#&7F | |

9C96 | ; | 020 059 | 14 3B | TRB &3B |

9C98 | . | 165 046 | A5 2E | LDA &2E |

9C9A | ) | 041 128 | 29 80 | AND#&80 |

9C9C | ; | 197 059 | C5 3B | CMP &3B |

9C9E | 208 030 | D0 1E | BNE 30 --> &9CBE | |

9CA0 | < | 165 060 | A5 3C | LDA &3C |

9CA2 | 0 | 197 048 | C5 30 | CMP &30 |

9CA4 | 208 025 | D0 19 | BNE 25 --> &9CBF | |

9CA6 | = | 165 061 | A5 3D | LDA &3D |

9CA8 | 1 | 197 049 | C5 31 | CMP &31 |

9CAA | 208 019 | D0 13 | BNE 19 --> &9CBF | |

9CAC | > | 165 062 | A5 3E | LDA &3E |

9CAE | 2 | 197 050 | C5 32 | CMP &32 |

9CB0 | 208 013 | D0 0D | BNE 13 --> &9CBF | |

9CB2 | ? | 165 063 | A5 3F | LDA &3F |

9CB4 | 3 | 197 051 | C5 33 | CMP &33 |

9CB6 | 208 007 | D0 07 | BNE 7 --> &9CBF | |

9CB8 | @ | 165 064 | A5 40 | LDA &40 |

9CBA | 4 | 197 052 | C5 34 | CMP &34 |

9CBC | 208 001 | D0 01 | BNE 1 --> &9CBF | |

9CBE | ` | 096 | 60 | RTS |

9CBF | j | 106 | 6A | ROR A |

9CC0 | E; | 069 059 | 45 3B | EOR &3B |

9CC2 | * | 042 | 2A | ROL A |

9CC3 | 169 001 | A9 01 | LDA#&01 | |

9CC5 | ` | 096 | 60 | RTS |