| Routines

13218: THE 'SINGLE OPERATION' SUBROUTINE (offset 59)

The address of this routine is found in the table of addresses. It is called via the calculator literal 59 by the routine at S_LETTER. This subroutine is only called from 10071 and is used to perform a single arithmetic operation. The offset that specifies which operation is to be performed is supplied to the calculator in the B register and subsequently transferred to the system variable BREG. The effect of calling this subroutine is essentially to make a jump to the appropriate subroutine for the single operation.
fp_calc_2 | 13218 | POP AF | Discard the RE_ENTRY address.
| 13219 | LD A,(23655) | Transfer the offset from BREG to A.
| 13222 | EXX | Enter the alternate register set.
| 13223 | JR SCAN_ENT | Jump back to find the required address; stack the RE_ENTRY address and jump to the subroutine for the operation.