53 lines
944 B
C
53 lines
944 B
C
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#include "vcpu.h"
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#include "mem.h"
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#include "screen.h"
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// Program Counter (16 bits but only 12 bits used (4096 memory addresses))
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unsigned short PC;
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// Index register (16 bits but only 12 bits used (4096 memory addresses))
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unsigned short I;
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// Stack register (16 bits)
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unsigned short S;
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// General purpose registers (8 bits each)
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// Note last one often used as a flag register
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unsigned char R[16];
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// Delay timer (8 bits)
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unsigned char DT;
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// Sound timer (8 bits)
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unsigned char ST;
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// Current VCPU state
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VCPU_State State;
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void VCPUInit(){
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PC=ADDR_ROM;
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}
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void VCPUFetch(){
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MemRead((char *)&(State.opcode),2,PC);
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PC+=2;
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}
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void VCPUDecode(){
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char X=(State.opcode<<4) & 0xF0;
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char Y=(State.opcode<<8) & 0xF0;
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char N=(State.opcode<<12) & 0xF0;
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char NN=(State.opcode<<8) & 0xFF;
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short NNN=(State.opcode<<4) & 0xFFF0;
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}
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void VCPUExecute(){
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switch(State.opcode){
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case 0x00E0:
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ScreenClear();
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break
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;;
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}
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}
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