5fc5dc13b2
Two 16 bit ints located at $FFE0 (0x7FE0 PC) in ROM and burned into SRAM starting at $701FFC, just before the ROM name
74 lines
1.9 KiB
NASM
74 lines
1.9 KiB
NASM
RomVersionSRAM = $701FFC
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;--------------------------------------------------------------------------------
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; Init_Primary
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;--------------------------------------------------------------------------------
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; This can be as inefficient as we want. Interrupts are off when this gets
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; called and it only gets called once ever during RESET.
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;--------------------------------------------------------------------------------
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Init_Primary:
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LDA #$00
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LDX #$00 ; initalize our ram
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-
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STA $7EC025, X
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STA $7F5000, X
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INX
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CPX #$10 : !BLT -
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LDX #$10 ; initalize more ram
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-
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STA $7F5000, X
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INX
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CPX #$FF : !BLT -
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LDX #$00
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-
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LDA $702000, X : CMP $00FFC0, X : BNE .clear
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INX
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CPX #$15 : !BLT -
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BRA .done
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.clear
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REP #$30 ; set 16-bit accumulator & index registers
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LDA.w #$0000
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-
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STA $700000, X
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INX
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CPX #$2000 : !BLT -
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SEP #$30 ; set 8-bit accumulator & index registers
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LDX #$00
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-
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LDA $00FFC0, X : STA $702000, X
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INX
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CPX #$15 : !BLT -
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LDX #$00
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-
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LDA RomVersion, X : STA RomVersionSRAM, X
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INX
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CPX #$04 : !BLT -
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.done
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REP #$20
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LDA.l OneMindTimer : STA.l !ONEMIND_TIMER
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SEP #$20
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LDA.b #$01 : STA $420D ; enable fastrom access on upper banks
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STA.l !ONEMIND_ID
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LDA.b #$10 : STA $BC ; set default player sprite bank
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LDA.b #$81 : STA $4200 ; thing we wrote over, turn on NMI & gamepad
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RTL
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;--------------------------------------------------------------------------------
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; Init_PostRAMClear
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;--------------------------------------------------------------------------------
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; This gets called after banks $7E and $7F get cleared, so if we need to
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; initialize RAM in those banks, do it here
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;--------------------------------------------------------------------------------
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Init_PostRAMClear:
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JSL MSUInit
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JSL InitRNGPointerTable
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JML $00D463 ; The original target of the jump table that we hijacked
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