sigonasr2/CHIP8Emulator
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Included original chipset functionality

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Co-authored-by: sigonasr2 <sigonasr2@gmail.com>
This commit is contained in:
sigonasr2 2023-01-06 00:26:15 -06:00
parent 06bc97ade9
commit 229509bc3b
2 changed files with 25 additions and 5 deletions
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main.cpp
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@ -57,6 +57,7 @@ public:
std::mt19937 gen; //Standard mersenne_twister_engine seeded with rd() std::mt19937 gen; //Standard mersenne_twister_engine seeded with rd()
std::uniform_int_distribution<> distrib; std::uniform_int_distribution<> distrib;
std::array<Key,16>keymap{X,K1,K2,K3,Q,W,E,A,S,D,Z,C,K4,R,F,V}; std::array<Key,16>keymap{X,K1,K2,K3,Q,W,E,A,S,D,Z,C,K4,R,F,V};
bool USE_ORIGINAL_CHIP8_SET=true;
std::string Display8(int number){ std::string Display8(int number){
std::bitset<8>numb(number); std::bitset<8>numb(number);
@ -207,7 +208,14 @@ public:
reg[X]-=reg[Y]; reg[X]-=reg[Y];
}break; }break;
case 0x6:{//Shift Right case 0x6:{//Shift Right
//reg[X]=reg[Y]; if (USE_ORIGINAL_CHIP8_SET){
/*
In the CHIP-8 interpreter for the original COSMAC VIP, this instruction did the following: It put the value of VY into VX, and then shifted the value in VX 1 bit to the right (8XY6) or left (8XYE). VY was not affected, but the flag register VF would be set to the bit that was shifted out.
However, starting with CHIP-48 and SUPER-CHIP in the early 1990s, these instructions were changed so that they shifted VX in place, and ignored the Y completely.
*/
reg[X]=reg[Y];
}
reg[0xF]=reg[X]&0x1; reg[0xF]=reg[X]&0x1;
reg[X]>>=1; reg[X]>>=1;
}break; }break;
@ -220,12 +228,16 @@ public:
}break; }break;
case 0xE:{//Shift Left case 0xE:{//Shift Left
//std::cout<<"Y is: "<<(int)Y<<std::endl; //std::cout<<"Y is: "<<(int)Y<<std::endl;
//reg[X]=reg[Y]; if (USE_ORIGINAL_CHIP8_SET){
std::cout<<"Before left shift: "<<(int)reg[X]<<std::endl; /*
In the CHIP-8 interpreter for the original COSMAC VIP, this instruction did the following: It put the value of VY into VX, and then shifted the value in VX 1 bit to the right (8XY6) or left (8XYE). VY was not affected, but the flag register VF would be set to the bit that was shifted out.
However, starting with CHIP-48 and SUPER-CHIP in the early 1990s, these instructions were changed so that they shifted VX in place, and ignored the Y completely.
*/
reg[X]=reg[Y];
}
reg[0xF]=(reg[X]&0x80)>>7; reg[0xF]=(reg[X]&0x80)>>7;
std::cout<<"Register F: "<<(int)reg[0xF]<<std::endl;
reg[X]<<=1; reg[X]<<=1;
std::cout<<"After Left shift: "<<(int)reg[X]<<std::endl;
}break; }break;
} }
}break; }break;
@ -321,11 +333,19 @@ public:
for (int i=0;i<=X;i++){ for (int i=0;i<=X;i++){
memory[index+i]=reg[i]; memory[index+i]=reg[i];
} }
if (USE_ORIGINAL_CHIP8_SET){
/*The original CHIP-8 interpreter for the COSMAC VIP actually incremented the I register while it worked. Each time it stored or loaded one register, it incremented I. After the instruction was finished, I would be set to the new value I + X + 1.*/
index+=X+1;
}
}break; }break;
case 0x65:{//Retrieves registers from V0 to VX in memory pointed by index. case 0x65:{//Retrieves registers from V0 to VX in memory pointed by index.
for (int i=0;i<=X;i++){ for (int i=0;i<=X;i++){
reg[i]=memory[index+i]; reg[i]=memory[index+i];
} }
if (USE_ORIGINAL_CHIP8_SET){
/*The original CHIP-8 interpreter for the COSMAC VIP actually incremented the I register while it worked. Each time it stored or loaded one register, it incremented I. After the instruction was finished, I would be set to the new value I + X + 1.*/
index+=X+1;
}
}break; }break;
} }
}break; }break;