developer's mag
main page
article
part 1
part 2
part 3
part 4
part 5
part 6
part 7
part 8
part 9
7 - Branching Codes
For branch instructions, the result of a successful test is a branch to the current address plus one, plus the value contained in the t register. In the case of a jump or subroutine call, the value is calculated identically. Note that because of the K flag, a ldt must be performed immediately before any conditional branching instruction for it to be interpreted as such.| beq | bge | bgeu; bcs | bgt |
| Branch if equal to zero (the Z flag was set). | Branch if greater than or equal - comparison of the sign flag and the overflow flag. | Branch if greater than or equal (unsigned) or branch if carry set. Test of C flag. | Branch if greater than. Similar to bge, except that zero is considered a test failure. |
| bgtu | ble | bleu | blt |
| Branch if greater than (for unsigned values). | Branch if less than or equal. | Branch if less than or equal (for unsigned values). | Branch if less than. |
| bltu; bcc | bmi | bne | bpl |
| Branch if less than (unsigned) or C flag cleared, which are equivalent. | Branch if minus (S flag set). | Branch if not equal. | Branch if plus (positive). |
| bra | bsr | bvc | bvs |
| Branch always (unconditionally). | Branch to subroutine - as with other branch instructions, the t value is added to the current position, plus one. | Branch if no overflow (V clear). | Branch if V set. |
| jmp (t) | jsr (t) | ||
| Jump to the location specified by the t register. | Perform a subroutine jump to the location specified by the t register. |
Previous Section
Next Section