doylet/dchip-8
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Increase CPU cycle count per frame to smooth input

Browse Source
This commit is contained in:
Doyle Thai 2017-04-07 17:35:55 +10:00
parent 77346c3674
commit 4a77719d89
4 changed files with 489 additions and 463 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

878
src/dchip8.cpp
View File

@ -290,31 +290,31 @@ FILE_SCOPE Chip8Controller dchip8_controller_map_input(PlatformInput input)
Chip8Controller result = {}; Chip8Controller result = {};
result.key[0x01] = input.key_1.isDown; result.key[0x01] = input.key_1.endedDown;
result.key[0x02] = input.key_2.isDown; result.key[0x02] = input.key_2.endedDown;
result.key[0x03] = input.key_3.isDown; result.key[0x03] = input.key_3.endedDown;
result.key[0x0C] = input.key_4.isDown; result.key[0x0C] = input.key_4.endedDown;
result.key[0x04] = input.key_q.isDown; result.key[0x04] = input.key_q.endedDown;
result.key[0x05] = input.key_w.isDown; result.key[0x05] = input.key_w.endedDown;
result.key[0x06] = input.key_e.isDown; result.key[0x06] = input.key_e.endedDown;
result.key[0x0D] = input.key_r.isDown; result.key[0x0D] = input.key_r.endedDown;
result.key[0x07] = input.key_a.isDown; result.key[0x07] = input.key_a.endedDown;
result.key[0x08] = input.key_s.isDown; result.key[0x08] = input.key_s.endedDown;
result.key[0x09] = input.key_d.isDown; result.key[0x09] = input.key_d.endedDown;
result.key[0x0E] = input.key_f.isDown; result.key[0x0E] = input.key_f.endedDown;
result.key[0x0A] = input.key_z.isDown; result.key[0x0A] = input.key_z.endedDown;
result.key[0x00] = input.key_x.isDown; result.key[0x00] = input.key_x.endedDown;
result.key[0x0B] = input.key_c.isDown; result.key[0x0B] = input.key_c.endedDown;
result.key[0x0F] = input.key_v.isDown; result.key[0x0F] = input.key_v.endedDown;
return result; return result;
} }
void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input, void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
PlatformMemory memory) PlatformMemory memory, u32 cyclesToEmulate)
{ {
DQNT_ASSERT(cpu.indexRegister >= 0 && cpu.indexRegister <= 0xFFF); DQNT_ASSERT(cpu.indexRegister >= 0 && cpu.indexRegister <= 0xFFF);
DQNT_ASSERT(cpu.programCounter >= 0 && cpu.programCounter <= 0xFFF); DQNT_ASSERT(cpu.programCounter >= 0 && cpu.programCounter <= 0xFFF);
@ -333,7 +333,7 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
if (cpu.state == chip8state_load_file) if (cpu.state == chip8state_load_file)
{ {
PlatformFile file = {}; PlatformFile file = {};
if (platform_open_file(L"roms/pong", &file)) if (platform_open_file(L"roms/brix", &file))
{ {
DQNT_ASSERT((cpu.INIT_ADDRESS + file.size) <= DQNT_ASSERT((cpu.INIT_ADDRESS + file.size) <=
memory.permanentMemSize); memory.permanentMemSize);
@ -359,7 +359,7 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
if (controller.key[keyVal]) if (controller.key[keyVal])
{ {
u8 regIndex = cpu.storeKeyToRegisterIndex; u8 regIndex = cpu.storeKeyToRegisterIndex;
DQNT_ASSERT(keyVal >= 0 && keyVal < 0x0F); DQNT_ASSERT(keyVal >= 0 && keyVal <= 0x0F);
cpu.registerArray[regIndex] = (u8)keyVal; cpu.registerArray[regIndex] = (u8)keyVal;
cpu.state = chip8state_running; cpu.state = chip8state_running;
@ -370,443 +370,468 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
if (cpu.state == chip8state_running) if (cpu.state == chip8state_running)
{ {
u8 opHighByte = mainMem[cpu.programCounter++]; bool earlyExit = false;
u8 opLowByte = mainMem[cpu.programCounter++]; for (u32 opCycle = 0; opCycle < cyclesToEmulate && !earlyExit;
opCycle++)
u8 opFirstNibble = (opHighByte & 0xF0);
switch (opFirstNibble)
{ {
case 0x00: u8 opHighByte = mainMem[cpu.programCounter++];
u8 opLowByte = mainMem[cpu.programCounter++];
u8 opFirstNibble = (opHighByte & 0xF0);
switch (opFirstNibble)
{ {
// CLS - 00E0 - Clear the display case 0x00:
if (opLowByte == 0xE0)
{ {
dchip8_init_display(renderBuffer); // CLS - 00E0 - Clear the display
} if (opLowByte == 0xE0)
// RET - 00EE - Return from subroutine
else if (opLowByte == 0xEE)
{
cpu.programCounter = cpu.stack[--cpu.stackPointer];
}
}
break;
case 0x10:
case 0x20:
{
u16 loc = ((0x0F & opHighByte) << 8) | opLowByte;
DQNT_ASSERT(loc <= 0x0FFF);
// JP addr - 1nnn - Jump to location nnn
if (opFirstNibble == 0x10)
{
// NOTE: Jump to loc, as per below
}
// Call addr - 2nnn - Call subroutine at nnn
else
{
DQNT_ASSERT(opFirstNibble == 0x20);
cpu.stack[cpu.stackPointer++] = cpu.programCounter;
DQNT_ASSERT(cpu.stackPointer < DQNT_ARRAY_COUNT(cpu.stack));
}
cpu.programCounter = loc;
}
break;
case 0x30:
case 0x40:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[regNum];
u8 valToCheck = opLowByte;
// SE Vx, byte - 3xkk - Skip next instruction if Vx == kk
if (opFirstNibble == 0x30)
{
if (*vx == valToCheck) cpu.programCounter += 2;
}
// SNE Vx, byte - 4xkk - Skip next instruction if Vx == kk
else
{
DQNT_ASSERT(opFirstNibble == 0x40);
if (*vx != valToCheck) cpu.programCounter += 2;
}
}
break;
// SE Vx, Vy - 5xy0 - Skip next instruction if Vx = Vy
case 0x50:
{
u8 firstRegNum = (0x0F & opHighByte);
DQNT_ASSERT(firstRegNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 secondRegNum = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(secondRegNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[firstRegNum];
u8 *vy = &cpu.registerArray[secondRegNum];
if (*vx == *vy) cpu.programCounter += 2;
}
break;
case 0x60:
case 0x70:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 valToOperateOn = opLowByte;
u8 *vx = &cpu.registerArray[regNum];
// LD Vx, byte - 6xkk - Set Vx = kk
if (opFirstNibble == 0x60)
{
*vx = valToOperateOn;
}
// ADD Vx, byte - 7xkk - Set Vx = Vx + kk
else
{
DQNT_ASSERT(opFirstNibble == 0x70);
*vx += valToOperateOn;
}
}
break;
case 0x80:
{
u8 firstRegNum = (0x0F & opHighByte);
DQNT_ASSERT(firstRegNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 secondRegNum = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(secondRegNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[firstRegNum];
u8 *vy = &cpu.registerArray[secondRegNum];
u8 opFourthNibble = (opLowByte & 0x0F);
// LD Vx, Vy - 8xy0 - Set Vx = Vy
if (opFourthNibble == 0x00)
{
*vx = *vy;
}
// OR Vx, Vy - 8xy1 - Set Vx = Vx OR Vy
else if (opFourthNibble == 0x01)
{
u8 result = (*vx | *vy);
*vx = result;
}
// AND Vx, Vy - 8xy2 - Set Vx = Vx AND Vy
else if (opFourthNibble == 0x02)
{
u8 result = (*vx & *vy);
*vx = result;
}
// XOR Vx, Vy - 8xy3 - Set Vx = Vx XOR Vy
else if (opFourthNibble == 0x03)
{
u8 result = (*vx ^ *vy);
*vx = result;
}
// ADD Vx, Vy - 8xy4 - Set Vx = Vx + Vy, set VF = carry
else if (opFourthNibble == 0x04)
{
u16 result = (*vx + *vy);
*vx = (result > 255) ? (u8)(result - 256) : (u8)result;
cpu.VF = (result > 255) ? 1 : 0;
}
// SUB Vx, Vy - 8xy5 - Set Vx = Vx - Vy, set VF = NOT borrow
else if (opFourthNibble == 0x05)
{
if (*vx > *vy)
{ {
cpu.VF = 1; dchip8_init_display(renderBuffer);
*vx -= *vy;
} }
// RET - 00EE - Return from subroutine
else if (opLowByte == 0xEE)
{
cpu.programCounter = cpu.stack[--cpu.stackPointer];
}
}
break;
case 0x10:
case 0x20:
{
u16 loc = ((0x0F & opHighByte) << 8) | opLowByte;
DQNT_ASSERT(loc <= 0x0FFF);
// JP addr - 1nnn - Jump to location nnn
if (opFirstNibble == 0x10)
{
// NOTE: Jump to loc, as per below
}
// Call addr - 2nnn - Call subroutine at nnn
else else
{ {
cpu.VF = 0; DQNT_ASSERT(opFirstNibble == 0x20);
*vx = (u8)(256 + *vx - *vy); cpu.stack[cpu.stackPointer++] = cpu.programCounter;
DQNT_ASSERT(cpu.stackPointer <
DQNT_ARRAY_COUNT(cpu.stack));
} }
cpu.programCounter = loc;
} }
// SHR Vx {, Vy} - 8xy6 - Set Vx = Vx SHR 1 break;
else if (opFourthNibble == 0x06)
{
if (*vx & 1)
cpu.VF = 1;
else
cpu.VF = 0;
*vx >>= 1; case 0x30:
} case 0x40:
// SUBN Vx {, Vy} - 8xy7 - Set Vx = Vy - Vx, set VF = NOT borrow
else if (opFourthNibble == 0x07)
{ {
if (*vy > *vx) u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[regNum];
u8 valToCheck = opLowByte;
// SE Vx, byte - 3xkk - Skip next instruction if Vx == kk
if (opFirstNibble == 0x30)
{ {
cpu.VF = 1; if (*vx == valToCheck) cpu.programCounter += 2;
*vx = *vy - *vx;
} }
// SNE Vx, byte - 4xkk - Skip next instruction if Vx == kk
else else
{ {
cpu.VF = 0; DQNT_ASSERT(opFirstNibble == 0x40);
*vx = (u8)(256 + *vy - *vx); if (*vx != valToCheck) cpu.programCounter += 2;
} }
} }
// SHL Vx {, Vy} - 8xyE - Set Vx = SHL 1 break;
else
{
DQNT_ASSERT(opFourthNibble == 0x0E);
if ((*vx >> 7) == 1)
cpu.VF = 1;
else
cpu.VF = 0;
*vx <<= 1; // SE Vx, Vy - 5xy0 - Skip next instruction if Vx = Vy
case 0x50:
{
u8 firstRegNum = (0x0F & opHighByte);
DQNT_ASSERT(firstRegNum <
DQNT_ARRAY_COUNT(cpu.registerArray));
u8 secondRegNum = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(secondRegNum <
DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[firstRegNum];
u8 *vy = &cpu.registerArray[secondRegNum];
if (*vx == *vy) cpu.programCounter += 2;
} }
} break;
break;
// SNE Vx, Vy - 9xy0 - Skip next instruction if Vx != Vy case 0x60:
case 0x90: case 0x70:
{
u8 firstRegNum = (0x0F & opHighByte);
DQNT_ASSERT(firstRegNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 secondRegNum = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(secondRegNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[firstRegNum];
u8 *vy = &cpu.registerArray[secondRegNum];
if (*vx != *vy) cpu.programCounter += 2;
}
break;
// LD I, addr - Annn - Set I = nnn
case 0xA0:
{
u16 valToSet = ((0x0F & opHighByte) << 8) | opLowByte;
cpu.indexRegister = valToSet;
}
break;
// JP V0, addr - Bnnn - Jump to location (nnn + V0)
case 0xB0:
{
u16 addr = (((0x0F & opHighByte) << 8) | opLowByte) + cpu.V0;
cpu.programCounter = addr;
}
break;
// RND Vx, byte - Cxkk - Set Vx = random byte AND kk
case 0xC0:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[regNum];
u8 randNum = (u8)dqnt_rnd_pcg_range(&pcgState, 0, 255);
u8 andBits = opLowByte;
DQNT_ASSERT(randNum >= 0 && randNum <= 255);
*vx = (randNum & andBits);
}
break;
// DRW Vx, Vy, nibble - Dxyn - Display n-byte sprite starting at mem
// location I at (Vx, Vy), set VF = collision
case 0xD0:
{
u8 xRegister = (0x0F & opHighByte);
u8 yRegister = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(xRegister < DQNT_ARRAY_COUNT(cpu.registerArray) &&
yRegister < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 initPosX = cpu.registerArray[xRegister];
u8 initPosY = cpu.registerArray[yRegister];
u8 readNumBytesFromMem = (0x0F & opLowByte);
// NOTE: can't be more than 16 in Y according to specs.
DQNT_ASSERT(readNumBytesFromMem < 16);
u8 *renderBitmap = (u8 *)renderBuffer.memory;
const i32 BYTES_PER_PIXEL = renderBuffer.bytesPerPixel;
i32 pitch = renderBuffer.width * BYTES_PER_PIXEL;
bool collisionFlag = false;
for (i32 i = 0; i < readNumBytesFromMem; i++)
{ {
u8 spriteBytes = mainMem[cpu.indexRegister + i]; u8 regNum = (0x0F & opHighByte);
u8 posY = initPosY + (u8)i; DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
if (posY >= renderBuffer.height) posY = 0; u8 valToOperateOn = opLowByte;
// NOTE: Flip the Y u8 *vx = &cpu.registerArray[regNum];
posY = ((u8)(renderBuffer.height-1) - posY); // LD Vx, byte - 6xkk - Set Vx = kk
if (opFirstNibble == 0x60)
const i32 ALPHA_BYTE_INTERVAL = renderBuffer.bytesPerPixel;
const i32 BITS_IN_BYTE = 8;
i32 baseBitShift = BITS_IN_BYTE - 1;
for (i32 shift = 0; shift < BITS_IN_BYTE; shift++)
{ {
u8 posX = initPosX + (u8)shift; *vx = valToOperateOn;
}
// ADD Vx, byte - 7xkk - Set Vx = Vx + kk
else
{
DQNT_ASSERT(opFirstNibble == 0x70);
*vx += valToOperateOn;
}
}
break;
if (posX >= renderBuffer.width) posX = 0; case 0x80:
u32 bitmapOffset = {
(posX * BYTES_PER_PIXEL) + (posY * pitch); u8 firstRegNum = (0x0F & opHighByte);
DQNT_ASSERT(firstRegNum <
DQNT_ARRAY_COUNT(cpu.registerArray));
// NOTE: Since we are using a 4bpp bitmap, let's use the u8 secondRegNum = (0xF0 & opLowByte) >> 4;
// alpha channel to determine if a pixel is on or not. DQNT_ASSERT(secondRegNum <
u32 *pixel = (u32 *)(&renderBitmap[bitmapOffset]); DQNT_ARRAY_COUNT(cpu.registerArray));
u8 alphaBit = (*pixel >> 24);
DQNT_ASSERT(alphaBit == 0 || alphaBit == 255); u8 *vx = &cpu.registerArray[firstRegNum];
bool pixelWasOn = (alphaBit == 255) ? true : false; u8 *vy = &cpu.registerArray[secondRegNum];
i32 bitShift = baseBitShift - shift; u8 opFourthNibble = (opLowByte & 0x0F);
bool spriteBit = ((spriteBytes >> bitShift) & 1); // LD Vx, Vy - 8xy0 - Set Vx = Vy
bool pixelIsOn = (pixelWasOn ^ spriteBit); if (opFourthNibble == 0x00)
{
*vx = *vy;
}
// OR Vx, Vy - 8xy1 - Set Vx = Vx OR Vy
else if (opFourthNibble == 0x01)
{
u8 result = (*vx | *vy);
*vx = result;
}
// AND Vx, Vy - 8xy2 - Set Vx = Vx AND Vy
else if (opFourthNibble == 0x02)
{
u8 result = (*vx & *vy);
*vx = result;
}
// XOR Vx, Vy - 8xy3 - Set Vx = Vx XOR Vy
else if (opFourthNibble == 0x03)
{
u8 result = (*vx ^ *vy);
*vx = result;
}
// ADD Vx, Vy - 8xy4 - Set Vx = Vx + Vy, set VF = carry
else if (opFourthNibble == 0x04)
{
u16 result = (*vx + *vy);
*vx = (result > 255) ? (u8)(result - 256) : (u8)result;
// NOTE: If caused a pixel to XOR into off, then this is cpu.VF = (result > 255) ? 1 : 0;
// known as a "collision" in chip8 }
if (pixelWasOn && !pixelIsOn) collisionFlag = true; // SUB Vx, Vy - 8xy5 - Set Vx = Vx - Vy, set VF = NOT borrow
else if (opFourthNibble == 0x05)
if (pixelIsOn) {
if (*vx > *vy)
{ {
*pixel = 0xFFFFFFFF; cpu.VF = 1;
*vx -= *vy;
} }
else else
{ {
*pixel = 0; cpu.VF = 0;
*vx = (u8)(256 + *vx - *vy);
}
}
// SHR Vx {, Vy} - 8xy6 - Set Vx = Vx SHR 1
else if (opFourthNibble == 0x06)
{
if (*vx & 1)
cpu.VF = 1;
else
cpu.VF = 0;
*vx >>= 1;
}
// SUBN Vx {, Vy} - 8xy7 - Set Vx = Vy - Vx, set VF = NOT
// borrow
else if (opFourthNibble == 0x07)
{
if (*vy > *vx)
{
cpu.VF = 1;
*vx = *vy - *vx;
}
else
{
cpu.VF = 0;
*vx = (u8)(256 + *vy - *vx);
}
}
// SHL Vx {, Vy} - 8xyE - Set Vx = SHL 1
else
{
DQNT_ASSERT(opFourthNibble == 0x0E);
if ((*vx >> 7) == 1)
cpu.VF = 1;
else
cpu.VF = 0;
*vx <<= 1;
}
}
break;
// SNE Vx, Vy - 9xy0 - Skip next instruction if Vx != Vy
case 0x90:
{
u8 firstRegNum = (0x0F & opHighByte);
DQNT_ASSERT(firstRegNum <
DQNT_ARRAY_COUNT(cpu.registerArray));
u8 secondRegNum = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(secondRegNum <
DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[firstRegNum];
u8 *vy = &cpu.registerArray[secondRegNum];
if (*vx != *vy) cpu.programCounter += 2;
}
break;
// LD I, addr - Annn - Set I = nnn
case 0xA0:
{
u16 valToSet = ((0x0F & opHighByte) << 8) | opLowByte;
cpu.indexRegister = valToSet;
}
break;
// JP V0, addr - Bnnn - Jump to location (nnn + V0)
case 0xB0:
{
u16 addr =
(((0x0F & opHighByte) << 8) | opLowByte) + cpu.V0;
cpu.programCounter = addr;
}
break;
// RND Vx, byte - Cxkk - Set Vx = random byte AND kk
case 0xC0:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[regNum];
u8 randNum = (u8)dqnt_rnd_pcg_range(&pcgState, 0, 255);
u8 andBits = opLowByte;
DQNT_ASSERT(randNum >= 0 && randNum <= 255);
*vx = (randNum & andBits);
}
break;
// DRW Vx, Vy, nibble - Dxyn - Display n-byte sprite starting at
// mem
// location I at (Vx, Vy), set VF = collision
case 0xD0:
{
u8 xRegister = (0x0F & opHighByte);
u8 yRegister = (0xF0 & opLowByte) >> 4;
DQNT_ASSERT(
xRegister < DQNT_ARRAY_COUNT(cpu.registerArray) &&
yRegister < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 initPosX = cpu.registerArray[xRegister];
u8 initPosY = cpu.registerArray[yRegister];
u8 readNumBytesFromMem = (0x0F & opLowByte);
// NOTE: can't be more than 16 in Y according to specs.
DQNT_ASSERT(readNumBytesFromMem < 16);
u8 *renderBitmap = (u8 *)renderBuffer.memory;
const i32 BYTES_PER_PIXEL = renderBuffer.bytesPerPixel;
i32 pitch = renderBuffer.width * BYTES_PER_PIXEL;
bool collisionFlag = false;
for (i32 i = 0; i < readNumBytesFromMem; i++)
{
u8 spriteBytes = mainMem[cpu.indexRegister + i];
u8 posY = initPosY + (u8)i;
if (posY >= renderBuffer.height) posY = 0;
// NOTE: Flip the Y
posY = ((u8)(renderBuffer.height - 1) - posY);
const i32 ALPHA_BYTE_INTERVAL =
renderBuffer.bytesPerPixel;
const i32 BITS_IN_BYTE = 8;
i32 baseBitShift = BITS_IN_BYTE - 1;
for (i32 shift = 0; shift < BITS_IN_BYTE; shift++)
{
u8 posX = initPosX + (u8)shift;
if (posX >= renderBuffer.width) posX = 0;
u32 bitmapOffset =
(posX * BYTES_PER_PIXEL) + (posY * pitch);
// NOTE: Since we are using a 4bpp bitmap, let's use
// the
// alpha channel to determine if a pixel is on or
// not.
u32 *pixel = (u32 *)(&renderBitmap[bitmapOffset]);
u8 alphaBit = (*pixel >> 24);
DQNT_ASSERT(alphaBit == 0 || alphaBit == 255);
bool pixelWasOn = (alphaBit == 255) ? true : false;
i32 bitShift = baseBitShift - shift;
bool spriteBit = ((spriteBytes >> bitShift) & 1);
bool pixelIsOn = (pixelWasOn ^ spriteBit);
// NOTE: If caused a pixel to XOR into off, then
// this is
// known as a "collision" in chip8
if (pixelWasOn && !pixelIsOn) collisionFlag = true;
if (pixelIsOn)
{
*pixel = 0xFFFFFFFF;
}
else
{
*pixel = 0;
}
}
}
cpu.VF = collisionFlag;
}
break;
case 0xE0:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 vx = cpu.registerArray[regNum];
DQNT_ASSERT(vx >= 0 && vx <= 0x0F);
DQNT_ASSERT(vx < DQNT_ARRAY_COUNT(controller.key));
bool skipNextInstruction = false;
// SKP Vx - Ex9E - Skip next instruction if key with the
// value
// of Vx is pressed
if (opLowByte == 0x9E)
{
skipNextInstruction = controller.key[vx];
}
// SKNP Vx - ExA1 - Skip next instruction if key with the
// value
// of Vx is not pressed
else
{
DQNT_ASSERT(opLowByte == 0xA1);
skipNextInstruction = !controller.key[vx];
}
if (skipNextInstruction) cpu.programCounter += 2;
}
break;
case 0xF0:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[regNum];
// LD Vx, DT - Fx07 - Set Vx = delay timer value
if (opLowByte == 0x07)
{
*vx = cpu.delayTimer;
}
// LD Vx, K - Fx0A - Wait for a key press, store the value
// of
// the key in Vx
else if (opLowByte == 0x0A)
{
cpu.state = chip8state_await_input;
cpu.storeKeyToRegisterIndex = regNum;
earlyExit = true;
}
// LD DT, Vx - Fx15 - Set delay timer = Vx
else if (opLowByte == 0x15)
{
cpu.delayTimer = *vx;
}
// LD ST, Vx - Fx18 - Set sound timer = Vx
else if (opLowByte == 0x18)
{
cpu.soundTimer = *vx;
}
// ADD I, Vx - Fx1E - Set I = I + Vx
else if (opLowByte == 0x1E)
{
cpu.indexRegister += *vx;
}
// LD F, Vx - Fx29 - Set I = location of sprite for digit Vx
else if (opLowByte == 0x29)
{
u8 hexCharFromFontSet = *vx;
DQNT_ASSERT(hexCharFromFontSet >= 0x00 &&
hexCharFromFontSet <= 0x0F);
const u32 START_ADDR_OF_FONT = 0;
const u32 BYTES_PER_FONT = 5;
cpu.I = START_ADDR_OF_FONT +
(hexCharFromFontSet * BYTES_PER_FONT);
}
// LD B, Vx - Fx33 - Store BCD representations of Vx in
// memory
// locations I, I+1 and I+2
else if (opLowByte == 0x33)
{
DQNT_ASSERT(regNum <
DQNT_ARRAY_COUNT(cpu.registerArray));
u8 vxVal = *vx;
const i32 NUM_DIGITS_IN_HUNDREDS = 3;
for (i32 i = 0; i < NUM_DIGITS_IN_HUNDREDS; i++)
{
u8 rem = vxVal % 10;
vxVal /= 10;
mainMem[cpu.I +
((NUM_DIGITS_IN_HUNDREDS - 1) - i)] = rem;
}
}
// LD [I], Vx - Fx55 - Store register V0 through Vx in
// memory
// starting at location I.
else if (opLowByte == 0x55)
{
for (u32 regIndex = 0; regIndex <= regNum; regIndex++)
{
u32 mem_offset = regIndex;
mainMem[cpu.indexRegister + mem_offset] =
cpu.registerArray[regIndex];
}
}
// LD [I], Vx - Fx65 - Read registers V0 through Vx from
// memory
// starting at location I.
else
{
DQNT_ASSERT(opLowByte == 0x65);
for (u32 regIndex = 0; regIndex <= regNum; regIndex++)
{
u32 mem_offset = regIndex;
cpu.registerArray[regIndex] =
mainMem[cpu.indexRegister + mem_offset];
} }
} }
} }
break;
cpu.VF = collisionFlag; };
} }
break;
case 0xE0:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 vx = cpu.registerArray[regNum];
DQNT_ASSERT(vx >= 0 && vx <= 0x0F);
DQNT_ASSERT(vx < DQNT_ARRAY_COUNT(controller.key));
bool skipNextInstruction = false;
// SKP Vx - Ex9E - Skip next instruction if key with the value
// of Vx is pressed
if (opLowByte == 0x9E)
{
skipNextInstruction = controller.key[vx];
}
// SKNP Vx - ExA1 - Skip next instruction if key with the value
// of Vx is not pressed
else
{
DQNT_ASSERT(opLowByte == 0xA1);
skipNextInstruction = !controller.key[vx];
}
if (skipNextInstruction) cpu.programCounter += 2;
}
break;
case 0xF0:
{
u8 regNum = (0x0F & opHighByte);
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 *vx = &cpu.registerArray[regNum];
// LD Vx, DT - Fx07 - Set Vx = delay timer value
if (opLowByte == 0x07)
{
*vx = cpu.delayTimer;
}
// LD Vx, K - Fx0A - Wait for a key press, store the value of
// the key in Vx
else if (opLowByte == 0x0A)
{
cpu.state = chip8state_await_input;
cpu.storeKeyToRegisterIndex = regNum;
}
// LD DT, Vx - Fx15 - Set delay timer = Vx
else if (opLowByte == 0x15)
{
cpu.delayTimer = *vx;
}
// LD ST, Vx - Fx18 - Set sound timer = Vx
else if (opLowByte == 0x18)
{
cpu.soundTimer = *vx;
}
// ADD I, Vx - Fx1E - Set I = I + Vx
else if (opLowByte == 0x1E)
{
cpu.indexRegister += *vx;
}
// LD F, Vx - Fx29 - Set I = location of sprite for digit Vx
else if (opLowByte == 0x29)
{
u8 hexCharFromFontSet = *vx;
DQNT_ASSERT(hexCharFromFontSet >= 0x00 &&
hexCharFromFontSet <= 0x0F);
const u32 START_ADDR_OF_FONT = 0;
const u32 BYTES_PER_FONT = 5;
cpu.I = START_ADDR_OF_FONT +
(hexCharFromFontSet * BYTES_PER_FONT);
}
// LD B, Vx - Fx33 - Store BCD representations of Vx in memory
// locations I, I+1 and I+2
else if (opLowByte == 0x33)
{
DQNT_ASSERT(regNum < DQNT_ARRAY_COUNT(cpu.registerArray));
u8 vxVal = *vx;
const i32 NUM_DIGITS_IN_HUNDREDS = 3;
for (i32 i = 0; i < NUM_DIGITS_IN_HUNDREDS; i++)
{
u8 rem = vxVal % 10;
vxVal /= 10;
mainMem[cpu.I + ((NUM_DIGITS_IN_HUNDREDS-1) - i)] = rem;
}
}
// LD [I], Vx - Fx55 - Store register V0 through Vx in memory
// starting at location I.
else if (opLowByte == 0x55)
{
for (u32 regIndex = 0; regIndex <= regNum; regIndex++)
{
u32 mem_offset = regIndex;
mainMem[cpu.indexRegister + mem_offset] =
cpu.registerArray[regIndex];
}
}
// LD [I], Vx - Fx65 - Read registers V0 through Vx from memory
// starting at location I.
else
{
DQNT_ASSERT(opLowByte == 0x65);
for (u32 regIndex = 0; regIndex <= regNum; regIndex++)
{
u32 mem_offset = regIndex;
cpu.registerArray[regIndex] =
mainMem[cpu.indexRegister + mem_offset];
}
}
}
break;
};
// IMPORTANT: Timers need to be decremented at a rate of 60hz. Since we // IMPORTANT: Timers need to be decremented at a rate of 60hz. Since we
// can run the interpreter faster than that, make sure we decrement // can run the interpreter faster than that, make sure we decrement
// timers at the fixed rate. // timers at the fixed rate.
@ -819,9 +844,16 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
{ {
cpu.elapsedTime = 0; cpu.elapsedTime = 0;
if (cpu.delayTimer > 0) cpu.delayTimer--; if (cpu.delayTimer > 0) cpu.delayTimer--;
// TODO(doyle): This needs to play a buzzing sound whilst timer
// > 0 if (cpu.soundTimer > 0)
if (cpu.soundTimer > 0) cpu.soundTimer--; {
cpu.soundTimer--;
if (cpu.soundTimer == 1)
{
// TODO(doyle): This needs to play a buzzing sound
// whilst timer > 0
}
}
} }
} }
else else

2
src/dchip8.h
View File

@ -4,6 +4,6 @@
#include "dchip8_platform.h" #include "dchip8_platform.h"
void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input, void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
PlatformMemory memory); PlatformMemory memory, u32 cyclesToEmulate);
#endif #endif

4
src/dchip8_platform.h
View File

@ -46,8 +46,8 @@ enum Key
typedef struct KeyState typedef struct KeyState
{ {
bool isDown; bool endedDown;
u32 transitionCount; u32 halfTransitionCount;
} KeyState; } KeyState;
typedef struct PlatformInput typedef struct PlatformInput

68
src/win32_dchip8.cpp
View File

@ -115,14 +115,13 @@ inline FILE_SCOPE LARGE_INTEGER win32_query_perf_counter_time()
return result; return result;
} }
FILE_SCOPE inline void win32_parse_key_msg(KeyState *key, MSG msg) FILE_SCOPE inline void win32_update_key(KeyState *key, bool isDown)
{ {
LPARAM lParam = msg.lParam; if (key->endedDown != isDown)
bool keyIsDown = ((lParam >> 30) & 1); {
bool keyTransitioned = ((lParam >> 31) & 1); key->endedDown = isDown;
key->halfTransitionCount++;
key->isDown = keyIsDown; }
if (keyTransitioned) key->transitionCount++;
} }
FILE_SCOPE void win32_process_messages(HWND window, PlatformInput *input) FILE_SCOPE void win32_process_messages(HWND window, PlatformInput *input)
@ -137,37 +136,38 @@ FILE_SCOPE void win32_process_messages(HWND window, PlatformInput *input)
case WM_KEYDOWN: case WM_KEYDOWN:
case WM_KEYUP: case WM_KEYUP:
{ {
bool isDown = (msg.message == WM_KEYDOWN);
switch (msg.wParam) switch (msg.wParam)
{ {
case VK_UP: win32_parse_key_msg(&input->up, msg); break; case VK_UP: win32_update_key(&input->up, isDown); break;
case VK_DOWN: win32_parse_key_msg(&input->down, msg); break; case VK_DOWN: win32_update_key(&input->down, isDown); break;
case VK_LEFT: win32_parse_key_msg(&input->left, msg); break; case VK_LEFT: win32_update_key(&input->left, isDown); break;
case VK_RIGHT: win32_parse_key_msg(&input->right, msg); break; case VK_RIGHT: win32_update_key(&input->right, isDown); break;
case '1': win32_parse_key_msg(&input->key_1, msg); break; case '1': win32_update_key(&input->key_1, isDown); break;
case '2': win32_parse_key_msg(&input->key_2, msg); break; case '2': win32_update_key(&input->key_2, isDown); break;
case '3': win32_parse_key_msg(&input->key_3, msg); break; case '3': win32_update_key(&input->key_3, isDown); break;
case '4': win32_parse_key_msg(&input->key_4, msg); break; case '4': win32_update_key(&input->key_4, isDown); break;
case 'Q': win32_parse_key_msg(&input->key_q, msg); break; case 'Q': win32_update_key(&input->key_q, isDown); break;
case 'W': win32_parse_key_msg(&input->key_w, msg); break; case 'W': win32_update_key(&input->key_w, isDown); break;
case 'E': win32_parse_key_msg(&input->key_e, msg); break; case 'E': win32_update_key(&input->key_e, isDown); break;
case 'R': win32_parse_key_msg(&input->key_r, msg); break; case 'R': win32_update_key(&input->key_r, isDown); break;
case 'A': win32_parse_key_msg(&input->key_a, msg); break; case 'A': win32_update_key(&input->key_a, isDown); break;
case 'S': win32_parse_key_msg(&input->key_s, msg); break; case 'S': win32_update_key(&input->key_s, isDown); break;
case 'D': win32_parse_key_msg(&input->key_d, msg); break; case 'D': win32_update_key(&input->key_d, isDown); break;
case 'F': win32_parse_key_msg(&input->key_f, msg); break; case 'F': win32_update_key(&input->key_f, isDown); break;
case 'Z': win32_parse_key_msg(&input->key_z, msg); break; case 'Z': win32_update_key(&input->key_z, isDown); break;
case 'X': win32_parse_key_msg(&input->key_x, msg); break; case 'X': win32_update_key(&input->key_x, isDown); break;
case 'C': win32_parse_key_msg(&input->key_c, msg); break; case 'C': win32_update_key(&input->key_c, isDown); break;
case 'V': win32_parse_key_msg(&input->key_v, msg); break; case 'V': win32_update_key(&input->key_v, isDown); break;
case VK_ESCAPE: case VK_ESCAPE:
{ {
win32_parse_key_msg(&input->escape, msg); win32_update_key(&input->escape, isDown);
if (input->escape.isDown) globalRunning = false; if (input->escape.endedDown) globalRunning = false;
} }
break; break;
@ -279,7 +279,7 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
platformMemory.permanentMemSize = DQNT_ARRAY_COUNT(stackMemory); platformMemory.permanentMemSize = DQNT_ARRAY_COUNT(stackMemory);
QueryPerformanceFrequency(&globalQueryPerformanceFrequency); QueryPerformanceFrequency(&globalQueryPerformanceFrequency);
const f32 TARGET_FRAMES_PER_S = 540.0f; const f32 TARGET_FRAMES_PER_S = 30.0f;
f32 targetSecondsPerFrame = 1 / TARGET_FRAMES_PER_S; f32 targetSecondsPerFrame = 1 / TARGET_FRAMES_PER_S;
f32 frameTimeInS = 0.0f; f32 frameTimeInS = 0.0f;
globalRunning = true; globalRunning = true;
@ -300,13 +300,7 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
platformBuffer.height = globalRenderBitmap.height; platformBuffer.height = globalRenderBitmap.height;
platformBuffer.width = globalRenderBitmap.width; platformBuffer.width = globalRenderBitmap.width;
platformBuffer.bytesPerPixel = globalRenderBitmap.bytesPerPixel; platformBuffer.bytesPerPixel = globalRenderBitmap.bytesPerPixel;
dchip8_update(platformBuffer, platformInput, platformMemory); dchip8_update(platformBuffer, platformInput, platformMemory, 15);
for (i32 i = 0; i < DQNT_ARRAY_COUNT(platformInput.key); i++)
{
if (platformInput.key[i].isDown)
OutputDebugString(L"Key is down\n");
}
} }
//////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////