Rather stay with OFF_YEAR as it is an "officially" name.

[cc65] / libsrc / plus4 / plus4-stdser.s

diff --git a/libsrc/plus4/plus4-stdser.s b/libsrc/plus4/plus4-stdser.s
index a5aace9f4aa1b57d5eebda572429cc779c05b1ea..30569a31fdfc9a4b786c9bf8d103249573c28fca 100644 (file)
--- a/libsrc/plus4/plus4-stdser.s
+++ b/libsrc/plus4/plus4-stdser.s
@@ -133,10 +133,16 @@ ParityTable:
 ;
 ; UNINSTALL routine. Is called before the driver is removed from memory.
 ; Must return an SER_ERR_xx code in a/x.
-
+;
+; and:
+;
+; CLOSE: Close the port, disable interrupts and flush the buffer. Called
+; without parameters. Must return an error code in a/x.
+;
 
 INSTALL:
 UNINSTALL:
+CLOSE:
 
 ; Deactivate DTR and disable 6551 interrupts
 
@@ -164,7 +170,15 @@ OPEN:
 
 ; Initialize buffers
 
-        jsr     InitBuffers
+        ldx    #0
+        stx     Stopped
+               stx     RecvHead
+       stx     RecvTail
+       stx     SendHead
+       stx     SendTail
+        dex                             ; X = 255
+               stx     RecvFreeCnt
+       stx     SendFreeCnt
 
 ; Set the value for the control register, which contains stop bits, word
 ; length and the baud rate.
@@ -223,28 +237,6 @@ InvBaud:
         ldx     #>SER_ERR_BAUD_UNAVAIL
         rts
 
-;----------------------------------------------------------------------------
-; CLOSE: Close the port, disable interrupts and flush the buffer. Called
-; without parameters. Must return an error code in a/x.
-;
-
-CLOSE:
-
-; Stop interrupts, drop DTR
-
-       lda     #%00001010
-               sta     ACIA_CMD
-
-; Initalize buffers.
-
-        jsr     InitBuffers
-
-; Return OK
-
-        lda     #<SER_ERR_OK
-        tax                             ; A is zero
-               rts
-
 ;----------------------------------------------------------------------------
 ; GET: Will fetch a character from the receive buffer and store it into the
 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
@@ -342,17 +334,18 @@ STATUS: lda       ACIA_STATUS
 
 IOCTL:  lda     #<SER_ERR_INV_IOCTL     ; We don't support ioclts for now
         ldx     #>SER_ERR_INV_IOCTL
-;       rts                            ; Run into IRQ instead
+        rts                            ; Run into IRQ instead
 
 ;----------------------------------------------------------------------------
 ; IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
-; registers are already save, no parameters are passed and no return code
-; is expected.
+; registers are already save, no parameters are passed, but the carry flag
+; is clear on entry. The routine must return with carry set if the interrupt
+; was handled, otherwise with carry clear.
 ;
 
 IRQ:    lda            ACIA_STATUS     ; Check ACIA status for receive interrupt
        and     #$08
-               beq     @L9             ; Jump if no ACIA interrupt
+               beq     @L9             ; Jump if no ACIA interrupt (carry still clear)
         lda    ACIA_DATA       ; Get byte from ACIA
        ldx     RecvFreeCnt     ; Check if we have free space left
                beq     @L1             ; Jump if no space in receive buffer
@@ -362,14 +355,15 @@ IRQ:    lda       ACIA_STATUS     ; Check ACIA status for receive interrupt
        dec     RecvFreeCnt     ; Decrement free space counter
        cpx     #33             ; Check for buffer space low
                bcc     @L1             ; Assert flow control if buffer space low
-@L9:    rts
+        rts                     ; Return with carry set (interrupt handled)
 
 ; Assert flow control if buffer space too low
 
 @L1:   lda     RtsOff
        sta     ACIA_CMD
        sta     Stopped
-        rts
+        sec                     ; Interrupt handled
+@L9:    rts
 
 ;----------------------------------------------------------------------------
 ; Try to send a byte. Internal routine. A = TryHard
@@ -407,18 +401,3 @@ IRQ:    lda        ACIA_STATUS     ; Check ACIA status for receive interrupt
 .endproc
 
 
-;----------------------------------------------------------------------------
-; Initialize buffers
-
-InitBuffers:
-        ldx    #0
-        stx     Stopped
-               stx     RecvHead
-       stx     RecvTail
-       stx     SendHead
-       stx     SendTail
-        dex                             ; X = 255
-               stx     RecvFreeCnt
-       stx     SendFreeCnt
-        rts
-