Add special addressing functions for X, Y, N, etc
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5d82b8ee40
commit
67b3e37c72
1 changed files with 63 additions and 44 deletions
107
src/emu.cpp
107
src/emu.cpp
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@ -32,6 +32,31 @@ void EmulatorState::reset() {
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draw_dirty = true;
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}
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// reads 0x0NNN
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uint16_t readAddress(const uint16_t opcode) {
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return opcode & 0x0fff;
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}
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// reads 0x00NN
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uint8_t readNN(const uint16_t opcode) {
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return opcode & 0x00ff;
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}
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// reads 0x000N
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uint8_t readN(const uint16_t opcode) {
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return (opcode & 0x000f);
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}
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// reads 0x0X00
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uint8_t readX(const uint16_t opcode) {
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return (opcode & 0x0f00) >> 8;
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}
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// reads 0x00Y0
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uint8_t readY(const uint16_t opcode) {
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return (opcode & 0x00f0) >> 4;
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}
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typedef void (*cpu_func)(const uint16_t opcode);
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void null_func(const uint16_t opcode) {
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@ -91,24 +116,23 @@ void operation0(const uint16_t opcode) {
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// 1NNN
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void operation1(const uint16_t opcode) {
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const uint16_t nnn = opcode & 0x0fff;
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const auto nnn = readAddress(opcode);
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state.PC = nnn;
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}
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// 2NNN
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void operation2(const uint16_t opcode) {
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const uint16_t nnn = opcode & 0x0fff;
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const auto nnn = readAddress(opcode);
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state.stack[state.stack_pointer] = state.PC;
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state.stack_pointer++;
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state.stack[state.stack_pointer++] = state.PC;
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state.PC = nnn;
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}
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// 3XNN
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void operation3(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t nn = opcode & 0x00ff;
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const auto x = readX(opcode);
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const auto nn = readNN(opcode);
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if(state.v[x] == nn)
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state.PC += 4;
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@ -118,8 +142,8 @@ void operation3(const uint16_t opcode) {
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// 4XNN
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void operation4(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t nn = opcode & 0x00ff;
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const auto x = readX(opcode);
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const auto nn = readNN(opcode);
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if(state.v[x] != nn)
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state.PC += 4;
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@ -129,28 +153,26 @@ void operation4(const uint16_t opcode) {
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// 6XNN
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void operation6(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t nn = opcode & 0x00ff;
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const auto x = readX(opcode);
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const auto nn = readNN(opcode);
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state.v[x] = nn;
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state.PC += 2;
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}
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// &XNN
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void operation7(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t nn = opcode & 0x00ff;
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const auto x = readX(opcode);
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const auto nn = readNN(opcode);
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state.v[x] += nn;
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state.PC += 2;
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}
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// 8XY0
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void op8_func0(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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state.v[x] = state.v[y];
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state.PC += 2;
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@ -158,8 +180,8 @@ void op8_func0(const uint16_t opcode) {
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// 8XY1
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void op8_func2(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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state.v[x] = state.v[x] & state.v[y];
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state.PC += 2;
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@ -167,8 +189,8 @@ void op8_func2(const uint16_t opcode) {
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// 8XY3
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void op8_func3(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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state.v[x] = state.v[x] ^ state.v[y];
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state.PC += 2;
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@ -176,8 +198,8 @@ void op8_func3(const uint16_t opcode) {
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// 8XY4
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void op8_func4(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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// TODO: implement tests
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if(state.v[y] < (0xFF - state.v[x]))
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@ -191,8 +213,8 @@ void op8_func4(const uint16_t opcode) {
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// 8XY5
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void op8_func5(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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// TODO: implement tests
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if(state.v[y] > state.v[x])
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@ -206,7 +228,7 @@ void op8_func5(const uint16_t opcode) {
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// 8XY6
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void op8_func6(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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state.v[0xF] = (state.v[x] & 1);
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state.v[x] >>= 1;
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@ -230,8 +252,8 @@ void operation8(const uint16_t opcode) {
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// 9XY0
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void operation9(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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if(state.v[x] != state.v[y])
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state.PC += 4;
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@ -241,7 +263,7 @@ void operation9(const uint16_t opcode) {
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// ANNN
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void operationA(const uint16_t opcode) {
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const uint16_t nnn = opcode & 0x0fff;
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const auto nnn = readAddress(opcode);
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state.I = nnn;
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state.PC += 2;
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@ -249,8 +271,8 @@ void operationA(const uint16_t opcode) {
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// CXNN
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void operationC(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t nn = opcode & 0x00ff;
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const auto x = readX(opcode);
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const auto nn = readNN(opcode);
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srand(time(nullptr));
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state.v[x] = (rand() % 0xFF) & nn;
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@ -259,9 +281,9 @@ void operationC(const uint16_t opcode) {
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// DXYN
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void operationD(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const uint8_t y = (opcode & 0x00f0) >> 4;
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const uint8_t n = opcode & 0x000f;
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const auto x = readX(opcode);
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const auto y = readY(opcode);
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const auto n = readN(opcode);
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const uint8_t x_pos = state.v[x];
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const uint8_t y_pos = state.v[y];
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@ -295,7 +317,7 @@ void operationD(const uint16_t opcode) {
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// EX9E & EXA1
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void operationE(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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switch(opcode & 0x00ff) {
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case 0x9E:
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@ -319,7 +341,7 @@ void operationE(const uint16_t opcode) {
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// FX07
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void opF_func7(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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state.v[x] = state.delay_timer;
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@ -328,7 +350,7 @@ void opF_func7(const uint16_t opcode) {
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// FX0A
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void opF_funcA(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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for(int i = 0; i < 16; i++) {
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if(state.keys[i] != 0) {
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@ -340,7 +362,7 @@ void opF_funcA(const uint16_t opcode) {
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// FX55/FX65 & FX15
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void opF_func5(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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switch((opcode & 0x00F0) >> 4) {
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case 0x6:
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@ -377,25 +399,23 @@ void opF_func5(const uint16_t opcode) {
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// FX18
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void opF_func8(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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state.sound_timer = state.v[x];
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state.PC += 2;
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}
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// FX29
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void opF_func9(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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state.I = state.v[x] * 0x5;
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state.PC += 2;
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}
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// FX1E
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void opF_funcE(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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if((state.I + state.v[x]) > 0xFFF)
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state.v[15] = 1;
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@ -403,13 +423,12 @@ void opF_funcE(const uint16_t opcode) {
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state.v[15] = 0;
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state.I += state.v[x];
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state.PC += 2;
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}
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// FX33
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void opF_func3(const uint16_t opcode) {
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const uint8_t x = (opcode & 0x0f00) >> 8;
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const auto x = readX(opcode);
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int decimal_rep = state.v[x];
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