| Routines

13574: THE 'LESS THAN ZERO' OPERATION (offset 54)

The address of this routine is found in the table of addresses. It is called via the calculator literal 54 by the routines at NEXT_LOOP, PRINT_FP, int, get_argt and atn. This subroutine returns a 'last value' of one if the present 'last value' is less than zero and zero otherwise. It is also used by other subroutines to 'jump on minus'.
Input
HL | Address of the first byte of the number
less_0 | 13574 | XOR A | Clear the A register.
This entry point is used by the routine at greater_0 with A=255.
SIGN_TO_C | 13575 | INC HL | Point to the sign byte.
| 13576 | XOR (HL) | The carry is reset for a positive number and set for a negative number; when entered from greater_0 the opposite sign goes to the carry.
| 13577 | DEC HL
| 13578 | RLCA
This routine continues into FP_0_1.