diff options
Diffstat (limited to 'src/sched.asm')
| -rw-r--r-- | src/sched.asm | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/src/sched.asm b/src/sched.asm index c871f7a..a540c49 100644 --- a/src/sched.asm +++ b/src/sched.asm @@ -31,13 +31,14 @@ SchedRunFirst:: ; caller when this task is eventually rescheduled. ; ----------------------------------------------------------------------------- SchedYield:: - call FindNextReady ; DE = &next PCB + call FindNextReady ; DE = &next PCB, CF if none runnable + ret c ; nobody else ready: keep running current call hSwitchTo ret ; ----------------------------------------------------------------------------- -; FindNextReady - round-robin from wSchedNext. out: DE = &PCB (updates cursor) -; Scaffold: assumes at least one PS_READY task exists. +; FindNextReady - round-robin from wSchedNext. +; out: DE = &PCB and CF clear on success; CF set if nothing is PS_READY. ; ----------------------------------------------------------------------------- FindNextReady:: ld a, [wSchedNext] @@ -56,14 +57,13 @@ FindNextReady:: pop af ; restore candidate slot dec b jr nz, .scan - ; nothing ready: fall back to slot 0 (idle behavior) - xor a - call PcbPtr + scf ; nothing runnable ret .found pop af ; A = chosen slot ld [wSchedNext], a call PcbPtr ; DE = &PCB + and a ; clear carry ret ; ----------------------------------------------------------------------------- |