Commit 233e36ae authored by Amanda Cameron's avatar Amanda Cameron
Browse files

Let's avoid clobbering the C/C++ softregs in the ZeroPage when we get an irq/nmi.

parent bded4e39

src/asm/dma.S

0 → 100644
+23 −0
Original line number Diff line number Diff line 
.macro _setup_dma src, dest, size

    lda #<src

    sta $E041

    lda #>src

    sta $E042



    lda #<dest

    sta $E043

    lda #>dest

    sta $E044



    lda #<size

    sta $E045

    lda #>size

    sta $E045

.endmacro



.macro dma_copy src, dest, size

    _setup_dma src, dest, size



    ; Execute the DMA.

    stz $E040

.endmacro
 
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src/asm/state.inc

0 → 100644
+25 −0
Original line number Diff line number Diff line 
.include "asm/dma.S"



.macro save_state addr

    pha

    phx

    phy



    ; DMA the Zero Page to the slot.

    dma_copy $0000, addr, $100

.endmacro



.macro load_state addr

    ; DMA the slot to the zero page.

    dma_copy addr, $0000, $100



    ply

    plx

    pla

.endmacro





.macro state_slot label

label:

    .res $100

.endmacro
 
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src/lib/crt0/irq.S

+11 −16
Original line number Diff line number Diff line 
.setcpu "65c02"

.include "asm/debug.inc"

.include "asm/3op-bits.inc"

.include "asm/state.inc"



.segment "DATA"

.bss



state_slot irq_state

state_slot nmi_state



.code

.import _handle_timer_a: absolute, _handle_timer_b: absolute

.import _handle_keyboard: absolute, _handle_signal: absolute

.import _handle_software_irq: absolute



.segment "CODE"

.importzp _tmp0



; Check the handler's non-null, if so call it.
@@ -75,9 +80,7 @@ init_irq: 
    rts



irq:

    pha

    phx

    phy

    save_state irq_state



    debug_tag #$D0
@@ -146,21 +149,13 @@ irq: 
@end:

    debug_tag #$DF



    ply

    plx

    pla



    load_state irq_state

    rti



nmi:

    pha

    phx

    phy

    save_state nmi_state



    debug_tag #$DD



    ply

    plx

    pla



    load_state nmi_state

    rti
 
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