39 lines
758 B
ArmAsm
39 lines
758 B
ArmAsm
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default_nmi_handler:
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// Implemented according to Compute's Mapping the Commodore 64, page 74
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// and to https://www.c64-wiki.com/wiki/Interrupt
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// Save registers, sequence according to Compute's Mapping the Commodore 64, page 73
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pha
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#if CONFIG_CPU_MOS_6502
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txa
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pha
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tya
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pha
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#else
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phx
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phy
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#endif
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// XXX: RS-232 support is not implemented
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// XXX confirm NMIs from CIA, or no other NMI will arrive!
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jsr cartridge_check
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bne !+
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jmp (ICART_WARM_START)
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!:
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// According to C64 Wiki, if STOP key is pressed, the routine assumes warm start request
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jsr JSTOP
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bcs !+
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jmp return_from_interrupt // no STOP pressed
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!:
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// STOP + RESTORE - clean the address of the BRK instruction (it's not BRK) first
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lda #$00
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sta CMP0+0
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sta CMP0+1
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jmp (CBINV)
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