Removed IRQ support from TGI drivers.

All but one TGI drivers didn't use IRQs. Especially when the TGI driver kernel was the only .interruptor this meant quite some unnecessary overhead because it pulled in the whole IRQ infrastructure.

The one driver using IRQs (the graphics driver for the 160x102x16 mode on the Lynx) now uses a library reference to set up a JMP to its IRQ handler.

libsrc/lynx/libref.s

@@ -2,9 +2,8 @@
 ; Oliver Schmidt, 2013-05-31
 ;
 
-        .export         joy_libref, ser_libref, tgi_libref
+        .export         joy_libref, ser_libref
         .import         _exit
 
 joy_libref      := _exit
 ser_libref      := _exit
-tgi_libref      := _exit

libsrc/lynx/tgi/lynx-160-102-16.s

@@ -29,7 +29,7 @@
 
         .byte   $74, $67, $69           ; "tgi"
         .byte   TGI_API_VERSION         ; TGI API version number
-        .addr   $0000                   ; Library reference
+libref: .addr   $0000                   ; Library reference
         .word   160                     ; X resolution
         .word   102                     ; Y resolution
         .byte   16                      ; Number of drawing colors
@@ -64,7 +64,6 @@
         .addr   BAR
         .addr   TEXTSTYLE
         .addr   OUTTEXT
-        .addr   IRQ
 
 
 ; ------------------------------------------------------------------------
@@ -164,6 +163,18 @@ INSTALL:
         stz     BGINDEX
         stz     DRAWPAGE
         stz     SWAPREQUEST
+        lda     libref
+        ldx     libref+1
+        sta     ptr1
+        stx     ptr1+1
+        ldy     #1
+        lda     #<irq
+        sta     (ptr1),y
+        iny
+        lda     #>irq
+        sta     (ptr1),y
+        lda     #$4C            ; Jump opcode
+        sta     (ptr1)          ; Activate IRQ routine
         rts
 
 
@@ -175,6 +186,12 @@ INSTALL:
 ;
 
 UNINSTALL:
+        lda     libref
+        ldx     libref+1
+        sta     ptr1
+        stx     ptr1+1
+        lda     #$60            ; RTS opcode
+        sta     (ptr1)          ; Disable IRQ routine
         rts
 
 
@@ -466,14 +483,10 @@ SETDRAWPAGE:
         stx     DRAWPAGEH
         rts
 
-; ------------------------------------------------------------------------
-; IRQ: VBL interrupt handler
-;
-
-IRQ:
+irq:
         lda     INTSET          ; Poll all pending interrupts
         and     #VBL_INTERRUPT
-        beq     IRQEND          ; Exit if not a VBL interrupt
+        beq     @L0             ; Exit if not a VBL interrupt
 
         lda     SWAPREQUEST
         beq     @L0
@@ -485,7 +498,6 @@ IRQ:
         jsr     SETDRAWPAGE
         stz     SWAPREQUEST
 @L0:
-IRQEND:
         clc
         rts
 

libsrc/lynx/tgi_irq.s

@@ -0,0 +1,11 @@
+;
+; Oliver Schmidt, 2018-02-02
+;
+
+        .export         tgi_libref
+        .interruptor    tgi_irq         ; Export as IRQ handler
+
+        .data
+
+tgi_libref:
+tgi_irq:        .byte   $60, $00, $00   ; RTS plus two dummy bytes