implemented draw function in interpreter
This commit is contained in:
129
Interpreter.cpp
129
Interpreter.cpp
@@ -4,6 +4,44 @@
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namespace chocochip8 {
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constexpr uint16_t gcvLowResToHighResRowLookupTable[256] = {
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0x0000, 0x0003, 0x000C, 0x000F, 0x0030, 0x0033, 0x003C, 0x003F, 0x00C0, 0x00C3, 0x00CC, 0x00CF, 0x00F0, 0x00F3, 0x00FC, 0x00FF,
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0x0300, 0x0303, 0x030C, 0x030F, 0x0330, 0x0333, 0x033C, 0x033F, 0x03C0, 0x03C3, 0x03CC, 0x03CF, 0x03F0, 0x03F3, 0x03FC, 0x03FF,
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0x0C00, 0x0C03, 0x0C0C, 0x0C0F, 0x0C30, 0x0C33, 0x0C3C, 0x0C3F, 0x0CC0, 0x0CC3, 0x0CCC, 0x0CCF, 0x0CF0, 0x0CF3, 0x0CFC, 0x0CFF,
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0x0F00, 0x0F03, 0x0F0C, 0x0F0F, 0x0F30, 0x0F33, 0x0F3C, 0x0F3F, 0x0FC0, 0x0FC3, 0x0FCC, 0x0FCF, 0x0FF0, 0x0FF3, 0x0FFC, 0x0FFF,
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0x3000, 0x3003, 0x300C, 0x300F, 0x3030, 0x3033, 0x303C, 0x303F, 0x30C0, 0x30C3, 0x30CC, 0x30CF, 0x30F0, 0x30F3, 0x30FC, 0x30FF,
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0x3300, 0x3303, 0x330C, 0x330F, 0x3330, 0x3333, 0x333C, 0x333F, 0x33C0, 0x33C3, 0x33CC, 0x33CF, 0x33F0, 0x33F3, 0x33FC, 0x33FF,
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0x3C00, 0x3C03, 0x3C0C, 0x3C0F, 0x3C30, 0x3C33, 0x3C3C, 0x3C3F, 0x3CC0, 0x3CC3, 0x3CCC, 0x3CCF, 0x3CF0, 0x3CF3, 0x3CFC, 0x3CFF,
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0x3F00, 0x3F03, 0x3F0C, 0x3F0F, 0x3F30, 0x3F33, 0x3F3C, 0x3F3F, 0x3FC0, 0x3FC3, 0x3FCC, 0x3FCF, 0x3FF0, 0x3FF3, 0x3FFC, 0x3FFF,
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0xC000, 0xC003, 0xC00C, 0xC00F, 0xC030, 0xC033, 0xC03C, 0xC03F, 0xC0C0, 0xC0C3, 0xC0CC, 0xC0CF, 0xC0F0, 0xC0F3, 0xC0FC, 0xC0FF,
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0xC300, 0xC303, 0xC30C, 0xC30F, 0xC330, 0xC333, 0xC33C, 0xC33F, 0xC3C0, 0xC3C3, 0xC3CC, 0xC3CF, 0xC3F0, 0xC3F3, 0xC3FC, 0xC3FF,
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0xCC00, 0xCC03, 0xCC0C, 0xCC0F, 0xCC30, 0xCC33, 0xCC3C, 0xCC3F, 0xCCC0, 0xCCC3, 0xCCCC, 0xCCCF, 0xCCF0, 0xCCF3, 0xCCFC, 0xCCFF,
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0xCF00, 0xCF03, 0xCF0C, 0xCF0F, 0xCF30, 0xCF33, 0xCF3C, 0xCF3F, 0xCFC0, 0xCFC3, 0xCFCC, 0xCFCF, 0xCFF0, 0xCFF3, 0xCFFC, 0xCFFF,
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0xF000, 0xF003, 0xF00C, 0xF00F, 0xF030, 0xF033, 0xF03C, 0xF03F, 0xF0C0, 0xF0C3, 0xF0CC, 0xF0CF, 0xF0F0, 0xF0F3, 0xF0FC, 0xF0FF,
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0xF300, 0xF303, 0xF30C, 0xF30F, 0xF330, 0xF333, 0xF33C, 0xF33F, 0xF3C0, 0xF3C3, 0xF3CC, 0xF3CF, 0xF3F0, 0xF3F3, 0xF3FC, 0xF3FF,
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0xFC00, 0xFC03, 0xFC0C, 0xFC0F, 0xFC30, 0xFC33, 0xFC3C, 0xFC3F, 0xFCC0, 0xFCC3, 0xFCCC, 0xFCCF, 0xFCF0, 0xFCF3, 0xFCFC, 0xFCFF,
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0xFF00, 0xFF03, 0xFF0C, 0xFF0F, 0xFF30, 0xFF33, 0xFF3C, 0xFF3F, 0xFFC0, 0xFFC3, 0xFFCC, 0xFFCF, 0xFFF0, 0xFFF3, 0xFFFC, 0xFFFF
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};
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constexpr uint8_t gcvLowResFontData[80] = {
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0xF0, 0x90, 0x90, 0x90, 0xF0,
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0x20, 0x60, 0x20, 0x20, 0x70,
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0xF0, 0x10, 0xF0, 0x80, 0xF0,
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0xF0, 0x10, 0xF0, 0x10, 0xF0,
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0x90, 0x90, 0xF0, 0x10, 0x10,
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0xF0, 0x80, 0xF0, 0x10, 0xF0,
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0xF0, 0x80, 0xF0, 0x90, 0xF0,
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0xF0, 0x10, 0x20, 0x40, 0x40,
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0xF0, 0x90, 0xF0, 0x90, 0xF0,
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0xF0, 0x90, 0xF0, 0x10, 0xF0,
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0xF0, 0x90, 0xF0, 0x90, 0x90,
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0xE0, 0x90, 0xE0, 0x90, 0xE0,
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0xF0, 0x80, 0x80, 0x80, 0xF0,
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0xE0, 0x90, 0x90, 0x90, 0xE0,
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0xF0, 0x80, 0xF0, 0x80, 0xF0,
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0xF0, 0x80, 0xF0, 0x80, 0x80
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};
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Interpreter::Interpreter(unsigned ticksPerSecond, Display &display, Buzzer &buzzer, Keypad &keypad):
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mvMemory(scMemorySize),
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mCallStack{},
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@@ -12,7 +50,13 @@ Interpreter::Interpreter(unsigned ticksPerSecond, Display &display, Buzzer &buzz
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mrKeypad{keypad},
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mcTicksPerSecond{ticksPerSecond},
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mvSpecialReg{},
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mvReg{} {}
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mvReg{},
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mIsHighResMode{false} {
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// Font sprite data goes into the interpreter reserved memory area
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memcpy(mvMemory.data() + scLowRestFontAddr, gcvLowResFontData, sizeof(gcvLowResFontData));
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// Initialize any non-zero registers at startup
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mvSpecialReg[SR_PC] = scResetVector;
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}
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void Interpreter::tick() {
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// decodes all possible machine code arithmetic opcodes
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@@ -28,9 +72,9 @@ void Interpreter::tick() {
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unsigned inst = (mvMemory[pc] << 8) | mvMemory[pc + 1];
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// extract fields
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unsigned regDst = (inst & 0x0F00) >> 8; // destination register index
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unsigned regSrc = (inst & 0x00F0) >> 4; // source register index
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unsigned opcode = (inst & 0x000F); // arithmetic opcode
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unsigned iRegDst = (inst & 0x0F00) >> 8; // destination register index
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unsigned iRegSrc = (inst & 0x00F0) >> 4; // source register index
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unsigned opcode = (inst & 0x000F); // arithmetic opcode or sprite index
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unsigned imm8 = (inst & 0x00FF); // 8-bit immediate
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unsigned imm12 = (inst & 0x0FFF); // 12-bit immediate
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@@ -59,25 +103,25 @@ void Interpreter::tick() {
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mvSpecialReg[SR_PC] = imm12;
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break;
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case 0x3000: // 3XNN - skip if equal immediate
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executeArithmetic(Opcode::JEQ, regDst, imm8);
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executeArithmetic(Opcode::JEQ, iRegDst, imm8);
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break;
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case 0x4000: // 4XNN - skip if nonequal immediate
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executeArithmetic(Opcode::JNEQ, regDst, imm8);
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executeArithmetic(Opcode::JNEQ, iRegDst, imm8);
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break;
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case 0x5000: // 5XY0 - skip if equal
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executeArithmetic(Opcode::JEQ, regDst, mvReg[regSrc]);
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executeArithmetic(Opcode::JEQ, iRegDst, mvReg[iRegSrc]);
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break;
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case 0x6000: // 6XNN - load immediate
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executeArithmetic(Opcode::SET, regDst, imm8);
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executeArithmetic(Opcode::SET, iRegDst, imm8);
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break;
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case 0x7000: // 7XNN - increment
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executeArithmetic(Opcode::ADD, regDst, imm8);
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executeArithmetic(Opcode::ADD, iRegDst, imm8);
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break;
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case 0x8000: // 8XNN - general arithmetic
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executeArithmetic(opcodeMap[opcode], regDst, mvReg[regSrc]);
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executeArithmetic(opcodeMap[opcode], iRegDst, mvReg[iRegSrc]);
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break;
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case 0x9000: // 9XY0 - skip if nonequal
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executeArithmetic(Opcode::JNEQ, regDst, mvReg[regSrc]);
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executeArithmetic(Opcode::JNEQ, iRegDst, mvReg[iRegSrc]);
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break;
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case 0xA000: // ANNN - load I
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mvSpecialReg[SR_I] = imm12;
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@@ -86,9 +130,10 @@ void Interpreter::tick() {
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mvSpecialReg[SR_I] = mvReg[R_V0] + imm12;
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break;
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case 0xC000: // CXNN - load random
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executeArithmetic(Opcode::RAND, regDst, imm8);
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executeArithmetic(Opcode::RAND, iRegDst, imm8);
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break;
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case 0xD000: // DXYN - draw
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executeDraw(mvReg[iRegDst], mvReg[iRegSrc], opcode);
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break;
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case 0xE000: // EX9E, EXA1 - keypad access
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break;
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@@ -111,11 +156,11 @@ void Interpreter::tick() {
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}
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}
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void Interpreter::loadProgram(size_t where, char const* data, size_t count) {
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void Interpreter::loadProgram(char const* data, size_t count, size_t where) {
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if(where + count > scMemorySize) {
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throw std::out_of_range("program exceeds memory bounds or capacity");
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}
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memcpy(mvMemory.data(), data, count);
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memcpy(mvMemory.data() + where, data, count);
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}
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void Interpreter::executeArithmetic(Opcode opcode, int iReg, reg_t operand) {
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@@ -165,4 +210,60 @@ void Interpreter::executeArithmetic(Opcode opcode, int iReg, reg_t operand) {
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}
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}
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void Interpreter::executeDraw(uint8_t x, uint8_t y, uint8_t n) {
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size_t iMemAddr = mvSpecialReg[SR_I]; // address of the sprite data in memory
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int collisionCount = 0; // number of scanlines in which any pixel changes from on to off
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// coordinates are doubled in low resolution mode
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if(!mIsHighResMode) {
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x *= 2;
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y *= 2;
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}
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x %= gcWidth;
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y %= gcHeight;
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// make x=0 be the right side of the screen instead of the left
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x = gcWidth - x;
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// draw each row of the sprite
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for(int i = 0; i < (mIsHighResMode && n == 0 ? 16 : n); i++) {
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uint16_t spriteRowBits;
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if(mIsHighResMode) {
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// draws an 8xN sprite
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spriteRowBits = mvMemory[iMemAddr++] << 8;
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if(n == 0) {
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// draws an 16xN sprite, so fetch another byte from sprite data
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spriteRowBits |= mvMemory[iMemAddr++];
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}
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} else {
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// in low-res mode, each sprite pixel draws two on-screen pixels
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spriteRowBits = gcvLowResToHighResRowLookupTable[mvMemory[iMemAddr++]];
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}
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// convert to bitset and shift into absolute horizontal position on the screen
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Scanline spriteScanline(spriteRowBits);
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if(x < 16) {
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spriteScanline >>= (16 - x);
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} else {
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spriteScanline <<= (x - 16);
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}
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// we draw one scanline per sprite row in high-res mode, but twice in low-res mode
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for(int j = 0; j < (mIsHighResMode ? 1 : 2); j++) {
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Scanline &targetScanline = mrDisplay.mpFramebuffer->at(y + i * (mIsHighResMode ? 1 : 2) + j);
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if((targetScanline & spriteScanline) != 0) {
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collisionCount += 1;
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}
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// blit the sprite bitset into the screen
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targetScanline ^= spriteScanline;
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}
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// update state flags
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if(mIsHighResMode) {
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mvReg[R_VF] = collisionCount;
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} else {
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mvReg[R_VF] = (collisionCount > 0 ? 1 : 0);
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}
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}
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}
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}; // namespace chochochip8
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