49 lines
1.5 KiB
C
49 lines
1.5 KiB
C
// cpu.h
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// SplitBit CPU Emulator Core
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// Written by Anachronaut
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// 10/16/2024
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#ifndef CPU_H
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#define CPU_H
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#include <stdint.h>
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// How many Data Pointers the CPU has. The instructions that name one take a full
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// byte to do it, so the encoding would allow up to 256. The limit here is the size
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// of the register file and the cost of saving pointers across a CALL, not the
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// instruction format. Must be a power of two, so that the selector can be masked
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// down to a valid pointer.
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#define DATA_POINTERS 4
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// How many Data Pointers survive a CALL. The low numbered pointers are saved and
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// restored around a subroutine; the rest are left alone, so a subroutine can use
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// one to hand a pointer back to its caller the way Q hands back a byte. This is
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// deliberately independent of DATA_POINTERS: adding more pointers should not make
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// every CALL more expensive.
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#define PRESERVED_DATA_POINTERS 3
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#if PRESERVED_DATA_POINTERS > DATA_POINTERS
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#error "Cannot preserve more Data Pointers than the CPU has."
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#endif
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// The struct containing the CPU registers.
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typedef struct {
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uint8_t A;
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uint8_t B;
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uint8_t Q;
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uint8_t Status;
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uint16_t ProgramCounter;
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uint16_t DataPointer[DATA_POINTERS];
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uint16_t StackPointer;
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uint8_t *Program;
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uint8_t *Data;
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} CPURegisters;
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uint8_t executeOperation(uint8_t instruction, CPURegisters *cpu);
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void initializeCPU(CPURegisters *cpu, uint8_t *programMemory, uint8_t *dataMemory);
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void stepCPU(CPURegisters *cpu);
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#endif // CPU_H
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