| Routines

06528: THE 'COMPARE LINE NUMBERS' SUBROUTINE

Used by the routines at OUT_LINE and LINE_ADDR. The given line number in the BC register pair is matched against the addressed line number.
Input
BC | First line number
HL | Address of the second line number
Output
F | Zero flag set if the line numbers match
F | Carry flag set if the first line number is greater than the second
CP_LINES | 06528 | LD A,(HL) | Fetch the high byte of the addressed line number and compare it.
| 06529 | CP B
| 06530 | RET NZ | Return if they do not match.
| 06531 | INC HL | Next compare the low bytes.
| 06532 | LD A,(HL)
| 06533 | DEC HL
| 06534 | CP C
| 06535 | RET | Return with the carry flag set if the addressed line number has yet to reach the given line number.