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67 lines
2.2 KiB
67 lines
2.2 KiB
#include "common.h"
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//Edit these defines to determine the debug outputs
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//#define DEBUG //General debug things such as running out of memory
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//#define DISABLE_LDA_DEBUG //LDA had a error in development and this flag is used to disable error reporting from LDA
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//
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#define STACK_RAM_OFFSET 0x100
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typedef union{
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struct var_t{
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byte Carry : 1;
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byte Zero : 1;
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byte Interrupt : 1;
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byte Decimal : 1;
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byte Break : 1;
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byte ignored : 1;
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byte Overflow : 1;
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byte Negative : 1;
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}flags;
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byte data;
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}SR_t;
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//this is a union, 'flags' (the one with individual bits) and 'data' are synced, to write a byte to the SR write to data, to flip a individual bit write to flags
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// aka to set negative to false you do "cpu.SR.flags.Negative = 0;", to write a whole byte to the SR, where each bit of the byte represents a flip bit (negative, overflow, etc) do "cpu.SR.data = byte_data;"
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typedef struct{
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word address;
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byte value;
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} busTransaction; //this is the type we use for our addressing types, they resolve to this type which contains a value and address
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struct instruction;
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typedef struct CPU{
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word PC; //Program Counter
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byte A; //Accumulator
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byte X; //X reg
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byte Y; //Y reg
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SR_t SR; //Stack register
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byte SP; //Stack pointer
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struct instruction * opcodes; //opcodes struct;
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//not part of the ACTUAL cpu, but useful flags I use for emulation
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bool pcNeedsInc; //checks if CPU needs its PC incremented by the number of bytes of the opcode (all opcodes except the sub-routine ones, look for the flag in the code)
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}CPU;
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struct instruction{
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void (*microcode)(struct CPU *, word bytes, busTransaction (*addressing)(CPU *, word)); //generic definition for opcode funcs such as BRK, ORA, etc
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busTransaction (*mode)(struct CPU * cpu, word bytes); //check line 85
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char * name;
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char bytes;
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char cycles;
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};
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void printCpu(CPU * cpu); //debug functions
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void raiseError(unsigned int err, CPU * cpu);
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void handleErrors(CPU * cpu);
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void printRegisters(CPU * cpu);
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void cpuClock(CPU * cpu); //tick function
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void initCpu(CPU * cpu); //init cpu, allocate memory for opcode register and set flags to initial state
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