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/plus4/ser/plus4-stdser.s
+++ b/libsrc/plus4/ser/plus4-stdser.s
@@ -300,21 +300,23 @@ SER_PUT:
 ; Try to send

        ldx     SendFreeCnt
-        inx                             ; X = $ff?
+        cpx     #$ff                   ; Nothing to flush
        beq     @L2
        pha
        lda     #$00
        jsr     TryToSend
        pla

-; Put byte into send buffer & send
+; Reload SendFreeCnt after TryToSend

-@L2:    ldx     SendFreeCnt
-        bne     @L3
+        ldx     SendFreeCnt
+        bne     @L2
        lda     #SER_ERR_OVERFLOW      ; X is already zero
        rts

-@L3:    ldx     SendTail
+; Put byte into send buffer & send
+
+@L2:    ldx     SendTail
        sta     SendBuf,x
        inc     SendTail
        dec     SendFreeCnt