Add file loading to platform layer

dchip-8.vcxproj

@@ -73,7 +73,7 @@
   <PropertyGroup Label="UserMacros" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <OutDir>$(SolutionDir)\bin\</OutDir>
-    <IntDir>$(SolutionDir)\bin\</IntDir>
+    <IntDir>$(SolutionDir)</IntDir>
   </PropertyGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <ClCompile>

src/dchip8.cpp

@@ -1,8 +1,23 @@
+#ifndef _CRT_SECURE_NO_WARNINGS
+	#define _CRT_SECURE_NO_WARNINGS
+#endif
+
 #include "dchip8_platform.h"
 #include "dqnt.h"
+#include "stdio.h"
+
+enum Chip8State
+{
+	chip8state_init,
+	chip8state_load_file,
+	chip8state_running,
+	chip8state_off,
+};
 
 typedef struct Chip8CPU
 {
+	const u16 INIT_ADDRESS = 0x200;
+
 	union {
 		u8 registerArray[16];
 		struct
@@ -50,10 +65,12 @@ typedef struct Chip8CPU
 	u8 stackPointer;
 	u16 stack[16];
 
-	bool isInit;
+	enum Chip8State state;
 } Chip8CPU;
 
 FILE_SCOPE Chip8CPU     cpu;
+FILE_SCOPE RandPCGState pcgState;
+
 void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
                    PlatformMemory memory)
 {
@@ -82,22 +99,46 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 		bitmapBuffer[i] = color;
 	}
 
-	if (!cpu.isInit)
+	u8 *mainMem = (u8 *)memory.permanentMem;
+	if (cpu.state == chip8state_init)
 	{
 		DQNT_ASSERT(memory.permanentMemSize == (4096 / 4));
-		cpu.isInit = true;
 
 		// NOTE: Everything before 0x200 is reserved for the actual emulator
-		const u32 INIT_ADDRESS = 0x200;
+		cpu.programCounter     = cpu.INIT_ADDRESS;
-		cpu.programCounter     = INIT_ADDRESS;
 		cpu.I                  = 0;
 		cpu.stackPointer       = 0;
 
-		// TODO(doyle): Load rom
+		const u32 SEED = 0x8293A8DE;
+		dqnt_rnd_pcg_seed(&pcgState, SEED);
+
+		cpu.state = chip8state_load_file;
 	}
 
-#if 0
+	if (cpu.state == chip8state_load_file)
-	u8 *mainMem   = (u8 *)memory.permanentMem;
+	{
+		PlatformFile file = {};
+		if (platform_open_file(L"roms/PONG", &file))
+		{
+			DQNT_ASSERT((cpu.INIT_ADDRESS + file.size) <=
+			            DQNT_ARRAY_COUNT(mainMem));
+
+			void *loadToAddr = (void *)(&mainMem[cpu.INIT_ADDRESS]);
+			if (platform_read_file(file, loadToAddr, (u32)file.size))
+			{
+				cpu.state = chip8state_running;
+			}
+			else
+			{
+				cpu.state = chip8state_off;
+			}
+
+			platform_close_file(&file);
+		}
+	}
+
+	if (cpu.state == chip8state_running)
+	{
 		u8 opHighByte = mainMem[cpu.programCounter++];
 		u8 opLowByte  = mainMem[cpu.programCounter++];
 
@@ -201,7 +242,6 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 					DQNT_ASSERT(opFirstNibble == 0x70);
 					cpu.registerArray[regNum] += valToOperateOn;
 				}
-
 			}
 			break;
 
@@ -246,7 +286,6 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 					*vx        = (u8)result;
 
 					if (result > 255) cpu.VF = (result > 255) ? 1 : 0;
-
 				}
 				// SUB Vx, Vy - 8xy5 - Set Vx = Vx - Vy, set VF = NOT borrow
 				else if (opLowByte == 0x05)
@@ -304,7 +343,7 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 				u8 *vx = &cpu.registerArray[firstRegNum];
 				u8 *vy = &cpu.registerArray[secondRegNum];
 
-			if (*vx != *vy) cpu.programCounter+= 2;
+				if (*vx != *vy) cpu.programCounter += 2;
 			}
 			break;
 
@@ -333,8 +372,8 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 				u8 andBits = opLowByte;
 				u8 *vx     = &cpu.registerArray[firstRegNum];
 
-			// TODO(doyle): Random umber
+				u8 randNum = (u8)dqnt_rnd_pcg_range(&pcgState, 0, 255);
-			*vx = (28 & opLowByte);
+				*vx        = (randNum & opLowByte);
 			}
 			break;
 
@@ -351,13 +390,15 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 				// TODO(doyle): Implement key checks
 				u8 checkKey = (0x0F & opHighByte);
 
-			// SKP Vx - Ex9E - Skip next instruction if key with the value of Vx
+				// SKP Vx - Ex9E - Skip next instruction if key with the value
+				// of Vx
 				// is pressed
 				bool skipNextInstruction = false;
 				if (opLowByte == 0x9E)
 				{
 				}
-			// SKNP Vx - ExA1 - Skip next instruction if key with the value of
+				// SKNP Vx - ExA1 - Skip next instruction if key with the value
+				// of
 				// Vx is not pressed
 				else
 				{
@@ -379,8 +420,8 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 				{
 					*vx = cpu.delayTimer;
 				}
-			// LD Vx, K - Fx0A - Wait for a key press, store the value of the
+				// LD Vx, K - Fx0A - Wait for a key press, store the value of
-			// key in Vx
+				// the key in Vx
 				else if (opLowByte == 0x0A)
 				{
 				}
@@ -435,5 +476,6 @@ void dchip8_update(PlatformRenderBuffer renderBuffer, PlatformInput input,
 			}
 			break;
 		};
-#endif
+	}
+
 }

src/dchip8_platform.h

@@ -53,4 +53,16 @@ typedef struct PlatformMemory
 	u32   transientMemSize;
 } PlatformMemory;
 
+typedef struct PlatformFile
+{
+	void *handle;
+	u64   size;
+} PlatformFile;
+
+// Return true if successful, false if not
+bool platform_open_file (const wchar_t *const file, PlatformFile *platformFile);
+// Return the number of bytes read
+u32  platform_read_file (PlatformFile file, void *buffer, u32 numBytesToRead);
+void platform_close_file(PlatformFile *file);
+
 #endif

src/dqnt.h

@@ -50,8 +50,17 @@ v2 V2i(i32 x, i32 y);
 ////////////////////////////////////////////////////////////////////////////////
 // String Ops
 ////////////////////////////////////////////////////////////////////////////////
-i32 dqnt_strcmp(const char *a, const char *b);
+bool  dqnt_char_is_digit   (char c);
-i32 dqnt_strlen(const char *a);
+bool  dqnt_char_is_alpha   (char c);
+bool  dqnt_char_is_alphanum(char c);
+
+i32   dqnt_strcmp (const char *a, const char *b);
+// Returns the length without the null terminator
+i32   dqnt_strlen (const char *a);
+char *dqnt_strncpy(char *dest, const char *src, i32 numChars);
+
+bool  dqnt_str_reverse(char *const buf, const i32 bufSize);
+i32   dqnt_str_to_i32 (char *const buf, const i32 bufSize);
 
 wchar_t dqnt_wchar_ascii_to_lower(wchar_t character);
 i32     dqnt_wstrcmp(const wchar_t *a, const wchar_t *b);
@@ -70,6 +79,8 @@ typedef struct RandPCGState
 void dqnt_rnd_pcg_seed (RandPCGState *pcg, u32 seed);
 // Returns a random number N between [0, 0xFFFFFFFF]
 u32  dqnt_rnd_pcg_next (RandPCGState *pcg);
+// Returns a random float N between [0.0, 1.0f]
+f32  dqnt_rnd_pcg_nextf(RandPCGState *pcg);
 // Returns a random integer N between [min, max]
 i32  dqnt_rnd_pcg_range(RandPCGState *pcg, i32 min, i32 max);
 
@@ -98,6 +109,24 @@ v2 V2i(i32 x, i32 y)
 ////////////////////////////////////////////////////////////////////////////////
 // String Ops
 ////////////////////////////////////////////////////////////////////////////////
+bool dqnt_char_is_digit(char c)
+{
+	if (c >= '0' && c <= '9') return true;
+	return false;
+}
+
+bool dqnt_char_is_alpha(char c)
+{
+	if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) return true;
+	return false;
+}
+
+bool dqnt_char_is_alphanum(char c)
+{
+	if (dqnt_char_is_alpha(c) || dqnt_char_is_digit(c)) return true;
+	return false;
+}
+
 i32 dqnt_strcmp(const char *a, const char *b)
 {
 	while ((*a) == (*b))
@@ -110,6 +139,86 @@ i32 dqnt_strcmp(const char *a, const char *b)
 	return (((*a) < (*b)) ? -1 : 1);
 }
 
+i32 dqnt_strlen(const char *a)
+{
+	i32 result = 0;
+	while (a[result]) result++;
+
+	return result;
+}
+
+char *dqnt_strncpy(char *dest, const char *src, i32 numChars)
+{
+	if (!dest) return NULL;
+	if (!src)  return dest;
+
+	for (i32 i  = 0; i < numChars; i++)
+		dest[i] = src[i];
+
+	return dest;
+}
+
+bool dqnt_str_reverse(char *const buf, const i32 bufSize)
+{
+	if (!buf) return false;
+	i32 mid = bufSize / 2;
+
+	for (i32 i = 0; i < mid; i++)
+	{
+		char tmp               = buf[i];
+		buf[i]                 = buf[(bufSize - 1) - i];
+		buf[(bufSize - 1) - i] = tmp;
+	}
+
+	return true;
+}
+
+i32 dqnt_str_to_i32(char *const buf, const i32 bufSize)
+{
+	if (!buf || bufSize == 0) return 0;
+
+	i32 index       = 0;
+	bool isNegative = false;
+	if (buf[index] == '-' || buf[index] == '+')
+	{
+		if (buf[index] == '-') isNegative = true;
+		index++;
+	}
+	else if (!dqnt_char_is_digit(buf[index]))
+	{
+		return 0;
+	}
+
+	i32 result = 0;
+	for (i32 i = index; i < bufSize; i++)
+	{
+		if (dqnt_char_is_digit(buf[i]))
+		{
+			result *= 10;
+			result += (buf[i] - '0');
+		}
+		else
+		{
+			break;
+		}
+	}
+
+	if (isNegative) result *= -1;
+
+	return result;
+}
+
+wchar_t dqnt_wchar_ascii_to_lower(wchar_t character)
+{
+	if (character >= L'A' && character <= L'Z')
+	{
+		i32 shiftOffset = L'a' - L'A';
+		character += (wchar_t)shiftOffset;
+	}
+
+	return character;
+}
+
 i32 dqnt_wstrcmp(const wchar_t *a, const wchar_t *b)
 {
 	while ((*a) == (*b))
@@ -137,17 +246,6 @@ void dqnt_wstrcat(const wchar_t *a, i32 lenA, const wchar_t *b, i32 lenB,
 	DQNT_ASSERT(outIndex <= outLen);
 }
 
-wchar_t dqnt_wchar_ascii_to_lower(wchar_t character)
-{
-	if (character >= L'A' && character <= L'Z')
-	{
-		i32 shiftOffset = L'a' - L'A';
-		character += (wchar_t)shiftOffset;
-	}
-
-	return character;
-}
-
 i32 dqnt_wstrlen(const wchar_t *a)
 {
 	i32 result = 0;
@@ -160,18 +258,6 @@ i32 dqnt_wstrlen(const wchar_t *a)
 	return result;
 }
 
-i32 dqnt_strlen(const char *a)
-{
-	i32 result = 0;
-	while ((*a))
-	{
-		result++;
-		a++;
-	}
-
-	return result;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // PCG (Permuted Congruential Generator) Random Number Generator
 ////////////////////////////////////////////////////////////////////////////////
@@ -180,7 +266,7 @@ i32 dqnt_strlen(const char *a)
 
 // Convert a randomized u32 value to a float value x in the range 0.0f <= x
 // < 1.0f. Contributed by Jonatan Hedborg
-FILE_SCOPE f32 dqnt_rnd_f32_normalized_from_u32_(u32 value)
+FILE_SCOPE f32 dqnt_rnd_f32_normalized_from_u32_internal(u32 value)
 {
 	u32 exponent = 127;
 	u32 mantissa = value >> 9;
@@ -189,7 +275,7 @@ FILE_SCOPE f32 dqnt_rnd_f32_normalized_from_u32_(u32 value)
 	return fresult - 1.0f;
 }
 
-FILE_SCOPE u64 dqnt_rnd_murmur3_avalanche64_(u64 h)
+FILE_SCOPE u64 dqnt_rnd_murmur3_avalanche64_internal(u64 h)
 {
 	h ^= h >> 33;
 	h *= 0xff51afd7ed558ccd;
@@ -202,11 +288,11 @@ FILE_SCOPE u64 dqnt_rnd_murmur3_avalanche64_(u64 h)
 void dqnt_rnd_pcg_seed(RandPCGState *pcg, u32 seed)
 {
 	u64 value     = (((u64)seed) << 1ULL) | 1ULL;
-	value         = dqnt_rnd_murmur3_avalanche64_(value);
+	value         = dqnt_rnd_murmur3_avalanche64_internal(value);
 	pcg->state[0] = 0U;
 	pcg->state[1] = (value << 1ULL) | 1ULL;
 	dqnt_rnd_pcg_next(pcg);
-	pcg->state[0] += dqnt_rnd_murmur3_avalanche64_(value);
+	pcg->state[0] += dqnt_rnd_murmur3_avalanche64_internal(value);
 	dqnt_rnd_pcg_next(pcg);
 }
 
@@ -221,7 +307,7 @@ u32 dqnt_rnd_pcg_next(RandPCGState *pcg)
 
 f32 dqnt_rnd_pcg_nextf(RandPCGState *pcg)
 {
-	return dqnt_rnd_f32_normalized_from_u32_(dqnt_rnd_pcg_next(pcg));
+	return dqnt_rnd_f32_normalized_from_u32_internal(dqnt_rnd_pcg_next(pcg));
 }
 
 i32 dqnt_rnd_pcg_range(RandPCGState *pcg, i32 min, i32 max)

src/unity_build.cpp

@@ -1,3 +1,5 @@
+#define _CRT_SECURE_NO_WARNINGS
+
 #define DQNT_IMPLEMENTATION
 #include "dqnt.h"
 

src/win32_dchip8.cpp

@@ -300,3 +300,55 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 
 	return 0;
 }
+
+void platform_close_file(PlatformFile *file)
+{
+	CloseHandle(file->handle);
+	file->handle = NULL;
+	file->size   = 0;
+}
+
+u32 platform_read_file(PlatformFile file, void *buffer, u32 numBytesToRead)
+{
+	DWORD numBytesRead = 0;
+	if (file.handle && buffer)
+	{
+		HANDLE win32Handle = file.handle;
+		BOOL result =
+		    ReadFile(win32Handle, buffer, numBytesToRead, &numBytesRead, NULL);
+
+		// TODO(doyle): 0 also means it is completing async, but still valid
+		if (result == 0)
+		{
+			win32_error_box(L"ReadFile() failed.", nullptr);
+		}
+
+	}
+
+	return numBytesRead;
+}
+
+FILE_SCOPE u32 buffer[15000];
+bool platform_open_file(const wchar_t *const file, PlatformFile *platformFile)
+{
+	HANDLE handle = CreateFile(file, GENERIC_READ | GENERIC_WRITE, 0, NULL,
+	                           OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+
+	if (handle == INVALID_HANDLE_VALUE)
+	{
+		win32_error_box(L"CreateFile() failed.", nullptr);
+		return false;
+	}
+
+	LARGE_INTEGER size;
+	if (GetFileSizeEx(handle, &size) == 0)
+	{
+		win32_error_box(L"GetFileSizeEx() failed.", nullptr);
+		return false;
+	}
+
+	platformFile->handle = handle;
+	platformFile->size   = size.QuadPart;
+
+	return true;
+}