Serial: Optimize SER_PUT

We don't need to reload SendFreeCnt if we don't jsr TryToSend.
2023-08-30 21:02:47 +02:00
parent 89af42e5cb
commit e8f5ad2471
7 changed files with 43 additions and 31 deletions
--- a/libsrc/atmos/ser/atmos-acia.s
+++ b/libsrc/atmos/ser/atmos-acia.s
@@ -269,20 +269,21 @@ SER_GET:
 SER_PUT:
        ; Try to send
        ldy     SendFreeCnt
-        iny                     ; Y = $FF?
+        cpy     #$FF            ; Nothing to flush
        beq     :+
        pha
        lda     #$00            ; TryHard = false
        jsr     TryToSend
        pla

-        ; Put byte into send buffer & send
-:       ldy     SendFreeCnt
+        ; Reload SendFreeCnt after TryToSend
+        ldy     SendFreeCnt
        bne     :+
        lda     #SER_ERR_OVERFLOW
        ldx     #0 ; return value is char
        rts

+        ; Put byte into send buffer & send
 :       ldy     SendTail
        sta     SendBuf,y
        inc     SendTail