Added wrapper for C level irq handling.

git-svn-id: svn://svn.cc65.org/cc65/trunk@5408 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/include/6502.h b/include/6502.h
index 08b82680025a0119a1e7e27394e8037af90f27b0..e0f161f92b7928f315c6dd604547c90d0f39ea4a 100644 (file)
--- a/include/6502.h
+++ b/include/6502.h
@@ -100,15 +100,27 @@ typedef void (*brk_handler) (void);
 /* Type of the break handler */
 
 void __fastcall__ set_brk (brk_handler f);
-/* Set the break vector to the given address, return the old address */
+/* Set the break vector to the given address */
 
 void reset_brk (void);
 /* Reset the break vector to the original value */
 
 
 
-/* End of 6502.h */
-#endif
+/* Possible returns for irq_handler() */
+#define IRQ_NOT_HANDLED        0
+#define IRQ_HANDLED    1
+
+typedef unsigned (*irq_handler) (void);
+/* Type of the C level interrupt request handler */
+
+void __fastcall__ set_irq (irq_handler f, void *stack_addr, size_t stack_size);
+/* Set the C level interrupt request vector to the given address */
 
+void reset_irq (void);
+/* Reset the C level interrupt request vector */
 
 
+
+/* End of 6502.h */
+#endif

diff --git a/libsrc/common/Makefile b/libsrc/common/Makefile
index 77a77e990d331699a9efcffbe316186fcb369112..83966a0042bcc581ebd80117848fb48041578582 100644 (file)
--- a/libsrc/common/Makefile
+++ b/libsrc/common/Makefile
@@ -123,6 +123,7 @@ S_OBJS =    _cwd.o                  \
                getcpu.o                \
                 getcwd.o                \
                getenv.o                \
+               interrupt.o             \
                isalnum.o               \
                isalpha.o               \
                isblank.o               \

diff --git a/libsrc/common/interrupt.s b/libsrc/common/interrupt.s
new file mode 100644 (file)
index 0000000..0b05ed8
--- /dev/null
+++ b/libsrc/common/interrupt.s
@@ -0,0 +1,102 @@
+;
+; Oliver Schmidt, 2012-01-18
+;
+; void __fastcall__ set_irq (irq_handler f, void *stack_addr, size_t stack_size);
+; void reset_irq (void);
+;
+
+       .export         _set_irq, _reset_irq
+       .interruptor    clevel_irq, 1           ; Export as low priority IRQ handler
+       .import         popax
+
+       .include        "zeropage.inc"
+
+       .macpack        generic
+
+
+.proc  _set_irq
+
+       ; Keep clevel_irq from being called right now
+       sei
+
+       ; Set irq stack pointer to stack_addr + stack_size
+       sta     irqsp
+       stx     irqsp+1
+       jsr     popax
+       add     irqsp
+       sta     irqsp
+       txa
+       adc     irqsp+1
+       sta     irqsp+1
+
+       ; Set irq vector to irq_handler
+       jsr     popax
+       sta     irqvec+1
+       stx     irqvec+2        ; Set the user vector
+
+       ; Restore interrupt requests and return
+       cli
+       rts
+
+.endproc
+
+
+.proc  _reset_irq
+
+       lda     #$00
+       sta     irqvec+3        ; High byte is enough
+       rts
+
+.endproc
+
+
+.proc  clevel_irq
+
+       ; Is C level interrupt request vector set?
+       lda     irqvec+3        ; High byte is enough
+       bne     @L1
+       clc                     ; Interrupt not handled
+       rts
+
+       ; Save our zero page locations
+@L1:   ldx     #zpspace-1
+@L2:    lda     sp,x
+       sta     zpsave,x
+       dex
+       bpl     @L2
+
+       ; Set C level interrupt stack
+       lda     irqsp
+       ldx     irqsp+1
+       sta     sp
+       stx     sp+1
+
+       ; Call C level interrupt request handler
+       jsr     irqvec
+       
+       ; Copy back our zero page content
+       ldx     #zpspace-1
+@L3:    ldy     zpsave,x
+       sty     sp,x
+       dex
+       bpl     @L3
+
+       ; Mark interrupt handled / not handled and return
+       lsr
+       rts
+
+.endproc
+
+; ---------------------------------------------------------------------------
+
+.data
+
+irqvec:        jmp     $00FF           ; Patched at runtime
+
+; ---------------------------------------------------------------------------
+
+.bss
+
+irqsp: .res    2
+
+zpsave: .res    zpspace