Initial commitmain

1 files changed, 985 insertions, 0 deletions

diff --git a/linux_handmade.cpp b/linux_handmade.cpp
new file mode 100644
index 0000000..1074685
--- /dev/null
+++ b/linux_handmade.cpp
@@ -0,0 +1,985 @@
+#include <stdio.h>
+#include <time.h>
+#include <x86intrin.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <dirent.h>
+
+#include <linux/limits.h>
+#include <linux/input.h>
+#include <alsa/asoundlib.h>
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#include <X11/keysymdef.h>
+#include <X11/extensions/Xrandr.h>
+
+#include "handmade.h"
+#include "linux_handmade.h"
+
+#define true 1
+#define false 0
+
+#define MAX_PLAYER_COUNT 4
+
+// NOTE(luca): Bits are layed out over multiple bytes.  This macro checks which byte the bit will be set in.
+#define IsEvdevBitSet(Bit, Array) (Array[(Bit) / 8] & (1 << ((Bit) % 8)))
+#define BytesNeededForBits(Bits) ((Bits + 7) / 8)
+
+global_variable b32 GlobalRunning;
+global_variable b32 GlobalPaused;
+
+void Memcpy(char *Dest, char *Source, size_t Count)
+{
+    while(Count--) *Dest++ = *Source++;
+}
+
+int StrLen(char *String)
+{
+    size_t Result = 0;
+    
+    while(*String++) Result++;
+    
+    return Result;
+}
+
+void CatStrings(size_t SourceACount, char *SourceA,
+                size_t SourceBCount, char *SourceB,
+                size_t DestCount, char *Dest)
+{
+    for(size_t Index = 0;
+        Index < SourceACount;
+        Index++)
+    {
+        *Dest++ = *SourceA++;
+    }
+    
+    for(size_t Index = 0;
+        Index < SourceBCount;
+        Index++)
+    {
+        *Dest++ = *SourceB++;
+    }
+}
+
+struct linux_init_alsa_result
+{
+    snd_pcm_t *PCMHandle;
+    snd_pcm_hw_params_t *PCMParams;
+};
+
+internal linux_init_alsa_result LinuxInitALSA()
+{
+    linux_init_alsa_result Result = {};
+    
+    int PCMResult = 0;
+    if((PCMResult = snd_pcm_open(&Result.PCMHandle, "default",
+                                 SND_PCM_STREAM_PLAYBACK, 0)) == 0) 
+    {
+        snd_pcm_hw_params_alloca(&Result.PCMParams);
+        snd_pcm_hw_params_any(Result.PCMHandle, Result.PCMParams);
+        u32 ChannelCount = 2;
+        u32 SampleRate = 48000;
+        
+        if((PCMResult = snd_pcm_hw_params_set_access(Result.PCMHandle, Result.PCMParams, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
+        {
+            // TODO(luca): Logging
+            // snd_strerror(pcm)
+        }
+        if((PCMResult = snd_pcm_hw_params_set_format(Result.PCMHandle, Result.PCMParams, SND_PCM_FORMAT_S16_LE)) < 0)
+        {
+            // TODO(luca): Logging
+        }
+        if((PCMResult = snd_pcm_hw_params_set_channels(Result.PCMHandle, Result.PCMParams, ChannelCount)) < 0)
+        {
+            // TODO(luca): Logging
+        }
+        if((PCMResult = snd_pcm_hw_params_set_rate_near(Result.PCMHandle, Result.PCMParams, &SampleRate, 0)) < 0) 
+        {
+            // TODO(luca): Logging
+        }    
+        if((PCMResult = snd_pcm_nonblock(Result.PCMHandle, 1)) < 0)
+        {
+            // TODO(luca): Logging
+        }
+        if((PCMResult = snd_pcm_reset(Result.PCMHandle)) < 0)
+        {
+            // TODO(luca): Logging
+        }
+        if((PCMResult = snd_pcm_hw_params(Result.PCMHandle, Result.PCMParams)) < 0)
+        {
+            // TODO(luca): Logging
+        }
+        
+    }
+    else
+    {
+        // TODO(luca): Logging
+    }
+    
+    return Result;
+}
+
+internal void LinuxGetAxisInfo(linux_gamepad *GamePad, linux_gamepad_axes_enum Axis, int AbsAxis)
+{
+    input_absinfo AxesInfo = {};
+    if(ioctl(GamePad->FileFD, EVIOCGABS(AbsAxis), &AxesInfo) != -1)
+    {
+        GamePad->Axes[Axis].Minimum = AxesInfo.minimum;
+        GamePad->Axes[Axis].Maximum = AxesInfo.maximum;
+        GamePad->Axes[Axis].Fuzz = AxesInfo.fuzz;
+        GamePad->Axes[Axis].Flat = AxesInfo.flat;
+    }
+}
+
+internal void LinuxOpenGamePad(char *FilePath, linux_gamepad *GamePad)
+{
+    GamePad->FileFD = open(FilePath, O_RDWR|O_NONBLOCK);
+    
+    if(GamePad->FileFD != -1)
+    {
+        int Version = 0;
+        int IsCompatible = true;
+        
+        // TODO(luca): Check versions
+        ioctl(GamePad->FileFD, EVIOCGVERSION, &Version);
+        ioctl(GamePad->FileFD, EVIOCGNAME(sizeof(GamePad->Name)), GamePad->Name);
+        
+        char SupportedEventBits[BytesNeededForBits(EV_MAX)] = {};
+        if(ioctl(GamePad->FileFD, EVIOCGBIT(0, sizeof(SupportedEventBits)), SupportedEventBits) != -1)
+        {
+            if(!IsEvdevBitSet(EV_ABS, SupportedEventBits))
+            {
+                // TODO(luca): Logging
+                IsCompatible = false;
+            }
+            if(!IsEvdevBitSet(EV_KEY, SupportedEventBits))
+            {
+                // TODO(luca): Logging
+                IsCompatible = false;
+            }
+        }
+        
+        char SupportedKeyBits[BytesNeededForBits(KEY_MAX)] = {};
+        if(ioctl(GamePad->FileFD, EVIOCGBIT(EV_KEY , sizeof(SupportedKeyBits)), SupportedKeyBits) != -1)
+        {
+            if(!IsEvdevBitSet(BTN_GAMEPAD, SupportedKeyBits))
+            {
+                // TODO(luca): Logging
+                IsCompatible = false;
+            }
+        }
+        
+        GamePad->SupportsRumble = IsEvdevBitSet(EV_FF, SupportedEventBits);
+        
+        if(IsCompatible)
+        {
+            // NOTE(luca): Map evdev axes to my enum.
+            LinuxGetAxisInfo(GamePad, LSTICKX, ABS_X);
+            LinuxGetAxisInfo(GamePad, LSTICKY, ABS_Y);
+            LinuxGetAxisInfo(GamePad, RSTICKX, ABS_RX);
+            LinuxGetAxisInfo(GamePad, RSTICKY, ABS_RY);
+            LinuxGetAxisInfo(GamePad, LSHOULDER, ABS_Z);
+            LinuxGetAxisInfo(GamePad, RSHOULDER, ABS_RZ);
+            LinuxGetAxisInfo(GamePad, DPADX, ABS_HAT0X);
+            LinuxGetAxisInfo(GamePad, DPADY, ABS_HAT0Y);
+            
+            Memcpy(GamePad->FilePath, FilePath, StrLen(FilePath));
+        }
+        else
+        {
+            close(GamePad->FileFD);
+            *GamePad = {};
+            GamePad->FileFD = -1;
+        }
+    }
+}
+
+// TODO(luca): Make this work in the case of multiple displays.
+internal r32 LinuxGetMonitorRefreshRate(Display *DisplayHandle, Window RootWindow)
+{
+    r32 Result = 0;
+    
+    void *LibraryHandle = dlopen("libXrandr.so", RTLD_NOW);
+    
+    if(LibraryHandle)
+    {
+        typedef XRRScreenResources *xrr_get_screen_resources(Display *Display, Window Window);
+        typedef XRRCrtcInfo *xrr_get_crtc_info(Display* Display, XRRScreenResources *Resources, RRCrtc Crtc);
+        
+        xrr_get_screen_resources *XRRGetScreenResources = (xrr_get_screen_resources *)dlsym(LibraryHandle, "XRRGetScreenResources");
+        xrr_get_crtc_info *XRRGetCrtcInfo = (xrr_get_crtc_info *)dlsym(LibraryHandle, "XRRGetCrtcInfo");
+        
+        XRRScreenResources *ScreenResources = XRRGetScreenResources(DisplayHandle, RootWindow);
+        
+        RRMode ActiveModeID = 0;
+        for(int CRTCIndex = 0;
+            CRTCIndex< ScreenResources->ncrtc;
+            CRTCIndex++)
+        {
+            XRRCrtcInfo *CRTCInfo = XRRGetCrtcInfo(DisplayHandle, ScreenResources, ScreenResources->crtcs[CRTCIndex]);
+            if(CRTCInfo->mode)
+            {
+                ActiveModeID = CRTCInfo->mode;
+            }
+        }
+        
+        r32 ActiveRate = 0;
+        for(int ModeIndex = 0;
+            ModeIndex < ScreenResources->nmode;
+            ModeIndex++)
+        {
+            XRRModeInfo ModeInfo = ScreenResources->modes[ModeIndex];
+            if(ModeInfo.id == ActiveModeID)
+            {
+                Assert(ActiveRate == 0);
+                Result = (r32)ModeInfo.dotClock / ((r32)ModeInfo.hTotal * (r32)ModeInfo.vTotal);
+            }
+        }
+        
+        dlclose(LibraryHandle);
+    }
+    
+    return Result;
+}
+
+internal void LinuxGetLibraryPath(char *Dest, char *ExecutablePath, char *LibraryFileName)
+{
+    size_t LastSlash = 0;
+    for(char *Scan = ExecutablePath;
+        *Scan;
+        Scan++)
+    {
+        if(*Scan == '/')
+        {
+            LastSlash = Scan - ExecutablePath;
+        }
+    }
+    
+    for(size_t Index = 0;
+        Index < LastSlash + 1;
+        Index++)
+    {
+        *Dest++ = *ExecutablePath++;
+    }
+    
+    while(*LibraryFileName) *Dest++ = *LibraryFileName++;
+}
+
+GAME_UPDATE_AND_RENDER(LinuxGameUpdateAndRenderStub) {}
+GAME_GET_SOUND_SAMPLES(LinuxGameGetSoundSamplesStub) {}
+
+internal linux_game_code LinuxLoadGameCode(char *LibraryPath)
+{
+    linux_game_code Result = {};
+    
+    Result.LibraryHandle = dlopen(LibraryPath, RTLD_NOW);
+    if(Result.LibraryHandle)
+    {
+        Result.UpdateAndRender = (game_update_and_render *)dlsym(Result.LibraryHandle, "GameUpdateAndRender");
+        Result.GetSoundSamples = (game_get_sound_samples *)dlsym(Result.LibraryHandle, "GameGetSoundSamples");
+    }
+    else
+    {
+        Result.UpdateAndRender = (game_update_and_render *)LinuxGameUpdateAndRenderStub;
+        Result.GetSoundSamples = (game_get_sound_samples *)LinuxGameGetSoundSamplesStub;
+    }
+    
+    return Result;
+}
+
+internal void LinuxUnloadGameCode(linux_game_code *Game)
+{
+    if(Game->LibraryHandle)
+    {
+        dlclose(Game->LibraryHandle);
+    }
+}
+
+internal void LinuxProcessKeyPress(game_button_state *ButtonState, b32 IsDown)
+{
+    if(ButtonState->EndedDown != IsDown)
+    {
+        ButtonState->EndedDown = IsDown;
+        ButtonState->HalfTransitionCount++;
+    }
+}
+
+internal void LinuxProcessPendingMessages(Display *DisplayHandle, Window WindowHandle,
+                                          Atom WM_DELETE_WINDOW, game_controller_input *KeyboardController)
+{
+    XEvent WindowEvent = {};
+    while(XPending(DisplayHandle) > 0)
+    {
+        XNextEvent(DisplayHandle, &WindowEvent);
+        switch (WindowEvent.type)
+        {
+            case KeyPress:
+            case KeyRelease:
+            {
+                KeySym keysym = XLookupKeysym(&WindowEvent.xkey, 0);
+                
+                b32 IsDown = (WindowEvent.type == KeyPress);
+                
+                if(0) {}
+                else if(keysym == XK_w)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->MoveUp, IsDown);
+                }
+                else if(keysym == XK_a)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->MoveLeft, IsDown);
+                }
+                else if(keysym == XK_r)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->MoveDown, IsDown);
+                }
+                else if(keysym == XK_s)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->MoveRight, IsDown);
+                }
+                else if(keysym == XK_Up)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->ActionUp, IsDown);
+                }
+                else if(keysym == XK_Left)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->ActionLeft, IsDown);
+                }
+                else if(keysym == XK_Down)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->ActionDown, IsDown);
+                }
+                else if(keysym == XK_Right)
+                {
+                    LinuxProcessKeyPress(&KeyboardController->ActionRight, IsDown);
+                }
+                else if(keysym == XK_p)
+                {
+                    if(IsDown)
+                    {
+                        GlobalPaused = !GlobalPaused;
+                    }
+                }
+                else if(keysym == XK_Escape ||
+                        keysym == XK_q)
+                {
+                    GlobalRunning = false;
+                }
+                
+            } break;
+            case DestroyNotify:
+            {
+                XDestroyWindowEvent *Event = (XDestroyWindowEvent *)&WindowEvent;
+                if(Event->window == WindowHandle)
+                {
+                    GlobalRunning = false;
+                }
+            } break;
+            
+            case ClientMessage:
+            {
+                XClientMessageEvent *Event = (XClientMessageEvent *)&WindowEvent;
+                if((Atom)Event->data.l[0] == WM_DELETE_WINDOW)
+                {
+                    XDestroyWindow(DisplayHandle, WindowHandle);
+                    GlobalRunning = false;
+                }
+            } break;
+        }
+    }
+    
+}
+
+internal void LinuxSetSizeHint(Display *DisplayHandle, Window WindowHandle,
+                               int MinWidth, int MinHeight,
+                               int MaxWidth, int MaxHeight)
+{
+    XSizeHints Hints = {};
+    if(MinWidth > 0 && MinHeight > 0) Hints.flags |= PMinSize;
+    if(MaxWidth > 0 && MaxHeight > 0) Hints.flags |= PMaxSize;
+    
+    Hints.min_width = MinWidth;
+    Hints.min_height = MinHeight;
+    Hints.max_width = MaxWidth;
+    Hints.max_height = MaxHeight;
+    
+    XSetWMNormalHints(DisplayHandle, WindowHandle, &Hints);
+}
+
+DEBUG_PLATFORM_READ_ENTIRE_FILE(DEBUGPlatformReadEntireFile)
+{
+    debug_read_file_result Result = {};
+    
+    int FD = open(FileName, O_RDONLY);
+    if(FD != -1)
+    {
+        struct stat FileStats = {};
+        fstat(FD, &FileStats);
+        Result.ContentsSize = FileStats.st_size;
+        Result.Contents = mmap(0, FileStats.st_size, PROT_READ, MAP_PRIVATE, FD, 0);
+        
+        close(FD);
+    }
+    
+    return Result;
+}
+
+DEBUG_PLATFORM_FREE_FILE_MEMORY(DEBUGPlatformFreeFileMemory)
+{
+    munmap(Memory, MemorySize);
+}
+
+DEBUG_PLATFORM_WRITE_ENTIRE_FILE(DEBUGPlatformWriteEntireFile)
+{
+    b32 Result = false;
+    
+    int FD = open(FileName, O_CREAT|O_WRONLY|O_TRUNC, 00600);
+    if(FD != -1)
+    {
+        if(write(FD, Memory, MemorySize) != MemorySize)
+        {
+            Result = true;
+        }
+        
+        close(FD);
+    }
+    
+    return Result;
+}
+
+internal struct timespec LinuxGetLastWriteTime(char *FilePath)
+{
+    struct timespec Result = {};
+    
+    struct stat LibraryFileStats = {};
+    if(!stat(FilePath, &LibraryFileStats))
+    {
+        Result = LibraryFileStats.st_mtim;
+    }
+    
+    return Result;
+}
+
+internal struct timespec LinuxGetWallClock()
+{
+    struct timespec Counter = {};
+    clock_gettime(CLOCK_MONOTONIC, &Counter);
+    return Counter;
+}
+
+internal s64 LinuxGetSecondsElapsed(struct timespec Start, struct timespec End)
+{
+    s64 Result = 0;
+    Result = ((s64)End.tv_sec*1000000000 + (s64)End.tv_nsec) - ((s64)Start.tv_sec*1000000000 + (s64)Start.tv_nsec);
+    return Result;
+}
+
+internal r32 LinuxNormalizeAxisValue(s32 Value, linux_gamepad_axis Axis)
+{
+    r32 Result = 0;
+    if(Value)
+    {
+        // ((value - min / max) - 0.5) * 2  
+        r32 Normalized = ((r32)((r32)(Value - Axis.Minimum) / (r32)(Axis.Maximum - Axis.Minimum)) - 0.5f)*2;
+        Result = Normalized;
+    }
+    Assert(Result <= 1.0f && Result >= -1.0f);
+    
+    return Result;
+}
+
+void LinuxDebugVerticalLine(game_offscreen_buffer *Buffer, int X, int Y, u32 Color)
+{
+    int Height = 32;
+    
+    if(X <= Buffer->Width && X >= 0 &&
+       Y <= Buffer->Height - Height && Y <= 0)
+    {
+        u8 *Row = (u8 *)Buffer->Memory + Y*Buffer->Pitch + X*Buffer->BytesPerPixel;
+        while(Height--)
+        {
+            *(u32 *)Row = Color;
+            Row += Buffer->Pitch;
+        }
+    }
+}
+
+int main(int ArgC, char *Args[])
+{
+    Display *DisplayHandle = XOpenDisplay(0);
+    
+    if(DisplayHandle)
+    {
+        Window RootWindow = XDefaultRootWindow(DisplayHandle);
+        int Screen = XDefaultScreen(DisplayHandle);
+        int Width = 800;
+        int Height = 600;
+        int ScreenBitDepth = 24;
+        XVisualInfo WindowVisualInfo = {};
+        if(XMatchVisualInfo(DisplayHandle, Screen, ScreenBitDepth, TrueColor, &WindowVisualInfo))
+        {
+            XSetWindowAttributes WindowAttributes = {};
+            WindowAttributes.bit_gravity = StaticGravity;
+            WindowAttributes.background_pixel = 0;
+            WindowAttributes.colormap = XCreateColormap(DisplayHandle, RootWindow, WindowVisualInfo.visual, AllocNone);
+            WindowAttributes.event_mask = StructureNotifyMask | KeyPressMask | KeyReleaseMask;
+            u64 WindowAttributeMask = CWBitGravity | CWBackPixel | CWColormap | CWEventMask;
+            
+            Window WindowHandle = XCreateWindow(DisplayHandle, RootWindow,
+                                                1920 - Width - 2, 1080 - Height - 2,
+                                                Width, Height,
+                                                0,
+                                                WindowVisualInfo.depth, InputOutput,
+                                                WindowVisualInfo.visual, WindowAttributeMask, &WindowAttributes);
+            if(WindowHandle)
+            {
+                XStoreName(DisplayHandle, WindowHandle, "Handmade Window");
+                LinuxSetSizeHint(DisplayHandle, WindowHandle, Width, Height, Width, Height);
+                
+                Atom WM_DELETE_WINDOW = XInternAtom(DisplayHandle, "WM_DELETE_WINDOW", False);
+                if(!XSetWMProtocols(DisplayHandle, WindowHandle, &WM_DELETE_WINDOW, 1))
+                {
+                    printf("Couldn't register WM_DELETE_WINDOW property\n");
+                }
+                
+                XClassHint ClassHint = {};
+                ClassHint.res_name = "Handmade Window";
+                ClassHint.res_class = "Handmade Window";
+                XSetClassHint(DisplayHandle, WindowHandle, &ClassHint);
+                
+                int BitsPerPixel = 32;
+                int BytesPerPixel = BitsPerPixel/8;
+                int WindowBufferSize = Width*Height*BytesPerPixel;
+                char *WindowBufferMemory = (char *)malloc(WindowBufferSize);
+                
+                XImage *WindowBuffer = XCreateImage(DisplayHandle, WindowVisualInfo.visual, WindowVisualInfo.depth, ZPixmap, 0, WindowBufferMemory, Width, Height, BitsPerPixel, 0);
+                GC DefaultGC = DefaultGC(DisplayHandle, Screen);
+                
+                char LibraryFullPath[PATH_MAX] = {};
+                char LibraryName[] = "handmade.so";
+                LinuxGetLibraryPath(LibraryFullPath, Args[0], LibraryName);
+                linux_game_code Game = LinuxLoadGameCode(LibraryFullPath);
+                Game.LibraryLastWriteTime = LinuxGetLastWriteTime(LibraryFullPath);
+                
+                game_memory GameMemory = {};
+                GameMemory.PermanentStorageSize = Megabytes(64);
+                GameMemory.TransientStorageSize = Gigabytes(1);
+                GameMemory.DEBUGPlatformReadEntireFile = DEBUGPlatformReadEntireFile;
+                GameMemory.DEBUGPlatformFreeFileMemory = DEBUGPlatformFreeFileMemory;
+                GameMemory.DEBUGPlatformWriteEntireFile = DEBUGPlatformWriteEntireFile;
+                
+#if HANDMADE_INTERNAL
+                void *BaseAddress = (void *)Terabytes(2);
+#else
+                void *BaseAddress = 0;
+#endif
+                
+                u64 TotalSize = GameMemory.PermanentStorageSize + GameMemory.TransientStorageSize;
+                GameMemory.PermanentStorage = (char *)mmap(BaseAddress, TotalSize, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_SHARED, -1, 0);
+                GameMemory.TransientStorage = (u8 *)GameMemory.PermanentStorage + GameMemory.PermanentStorageSize;
+                
+                game_input Input[2] = {};
+                game_input *NewInput = &Input[0];
+                game_input *OldInput = &Input[1];
+                
+                linux_gamepad GamePads[MAX_PLAYER_COUNT] = {};
+                for(int GamePadIndex = 0;
+                    GamePadIndex < MAX_PLAYER_COUNT;
+                    GamePadIndex++)
+                {
+                    GamePads[GamePadIndex].FileFD = -1;
+                }
+                
+                // TODO(luca): Run this once on startup to detect connected controllers and later with inotify when controllers are added.
+                char EventDirectoryName[] = "/dev/input/";
+                DIR *EventDirectory = opendir(EventDirectoryName);
+                struct dirent *Entry = 0;
+                int GamePadIndex = 0;
+                while((Entry = readdir(EventDirectory)))
+                {
+                    if(!strncmp(Entry->d_name, "event", sizeof("event") - 1))
+                    {
+                        char FilePath[PATH_MAX] = {};
+                        CatStrings(sizeof(EventDirectoryName) - 1, EventDirectoryName,
+                                   StrLen(Entry->d_name), Entry->d_name,
+                                   sizeof(FilePath) - 1, FilePath);
+                        if(GamePadIndex < MAX_PLAYER_COUNT)
+                        {
+                            linux_gamepad *GamePadAt = &GamePads[GamePadIndex];
+                            LinuxOpenGamePad(FilePath, GamePadAt);
+                            if(GamePadAt->FileFD != -1)
+                            {
+#if 0
+                                for(int AxesIndex = 0;
+                                    AxesIndex < AXES_COUNT;
+                                    AxesIndex++)
+                                {
+                                    linux_gamepad_axis Axis = GamePadAt->Axes[AxesIndex];
+                                    printf("min: %d, max: %d, fuzz: %d, flat: %d\n", Axis.Minimum, Axis.Maximum, Axis.Fuzz, Axis.Flat);
+                                }
+#endif
+                                GamePadIndex++;
+                            }
+                        }
+                        else
+                        {
+                            // TODO(luca): Logging
+                        }
+                    }
+                }
+                
+                game_offscreen_buffer OffscreenBuffer = {};
+                OffscreenBuffer.Memory = WindowBufferMemory;
+                OffscreenBuffer.Width = Width;
+                OffscreenBuffer.Height = Height;
+                OffscreenBuffer.BytesPerPixel = BytesPerPixel;
+                OffscreenBuffer.Pitch = Width*BytesPerPixel;
+                
+                int LastFramesWritten = 0;
+                unsigned int SampleRate, ChannelCount, TimePeriod, SampleCount;
+                snd_pcm_status_t *PCMStatus = 0;
+                snd_pcm_t* PCMHandle = 0;
+                snd_pcm_hw_params_t *PCMParams = 0;
+                snd_pcm_uframes_t PeriodSize = 0;
+                snd_pcm_uframes_t PCMBufferSize = 0;
+                
+                linux_init_alsa_result ALSAInit = LinuxInitALSA();
+                PCMHandle = ALSAInit.PCMHandle;
+                PCMParams = ALSAInit.PCMParams;
+                snd_pcm_hw_params_get_channels(PCMParams, &ChannelCount);
+                snd_pcm_hw_params_get_rate(PCMParams, &SampleRate, 0);
+                snd_pcm_hw_params_get_period_size(PCMParams, &PeriodSize, 0);
+                snd_pcm_hw_params_get_period_time(PCMParams, &TimePeriod, NULL);
+                snd_pcm_hw_params_get_buffer_size(PCMParams, &PCMBufferSize);
+                snd_pcm_status_malloc(&PCMStatus);
+                
+                char AudioSamples[PCMBufferSize];
+                u64 Periods = 2;
+                u32 BytesPerSample = (sizeof(s16)*ChannelCount);
+                
+#if 1              
+                r32 GameUpdateHz = 30;
+#else
+                r32 GameUpdateHz = LinuxGetMonitorRefreshRate(DisplayHandle, RootWindow);
+#endif
+                
+                thread_context ThreadContext = {};
+                
+                XMapWindow(DisplayHandle, WindowHandle);
+                XFlush(DisplayHandle);
+                
+                struct timespec LastCounter = LinuxGetWallClock();
+                struct timespec FlipWallClock = LinuxGetWallClock();
+                r32 TargetSecondsPerFrame = 1.0f / GameUpdateHz; 
+                
+                GlobalRunning = true;
+                
+                u64 LastCycleCount = __rdtsc();
+                while(GlobalRunning)
+                {
+                    
+#if HANDMADE_INTERNAL
+                    // NOTE(luca): Because gcc will first create an empty file and then write into it we skip trying to reload when the file is empty.
+                    struct stat FileStats = {};
+                    stat(LibraryFullPath, &FileStats);
+                    if(FileStats.st_size)
+                    {
+                        s64 SecondsElapsed = LinuxGetSecondsElapsed(Game.LibraryLastWriteTime, FileStats.st_mtim) / 1000/1000;
+                        if(SecondsElapsed > 0)
+                        {
+                            LinuxUnloadGameCode(&Game);
+                            Game = LinuxLoadGameCode(LibraryFullPath);
+                            Game.LibraryLastWriteTime = FileStats.st_mtim;
+                        }
+                    }
+#endif
+                    
+                    game_controller_input *OldKeyboardController = GetController(OldInput, 0);
+                    game_controller_input *NewKeyboardController = GetController(NewInput, 0);
+                    NewKeyboardController->IsConnected = true;
+                    
+                    LinuxProcessPendingMessages(DisplayHandle, WindowHandle, WM_DELETE_WINDOW, NewKeyboardController);
+                    
+                    // TODO(luca): Use buttonpress/release events instead so we query this less frequently.
+                    s32 MouseX = 0, MouseY = 0, MouseZ = 0; // TODO(luca): Support mousewheel?
+                    u32 MouseMask = 0;
+                    u64 Ignored;
+                    if(XQueryPointer(DisplayHandle, WindowHandle, 
+                                     &Ignored, &Ignored, (int *)&Ignored, (int *)&Ignored,
+                                     &MouseX, &MouseY, &MouseMask))
+                    {
+                        if(MouseX <= OffscreenBuffer.Width &&
+                           MouseX >= 0 &&
+                           MouseY <= OffscreenBuffer.Height &&
+                           MouseY >= 0)
+                        {
+                            NewInput->MouseY = MouseY;
+                            NewInput->MouseX = MouseX;
+                            NewInput->MouseButtons[0].EndedDown = ((MouseMask & Button1Mask) > 0); 
+                            NewInput->MouseButtons[1].EndedDown = ((MouseMask & Button2Mask) > 0); 
+                            NewInput->MouseButtons[2].EndedDown = ((MouseMask & Button3Mask) > 0); 
+                        }
+                    }
+                    
+                    for(int GamePadIndex = 0;
+                        GamePadIndex < MAX_PLAYER_COUNT;
+                        GamePadIndex++)
+                    {
+                        linux_gamepad *GamePadAt = &GamePads[GamePadIndex];
+                        
+                        if(GamePadAt->FileFD != -1)
+                        {
+                            game_controller_input *OldController = GetController(OldInput, 0);
+                            game_controller_input *NewController = GetController(NewInput, 0);
+                            
+                            // TODO(luca): What we really want is the last event. (or haltransitions)
+                            struct input_event InputEvents[64] = {};
+                            int BytesRead = 0;
+                            
+                            BytesRead = read(GamePadAt->FileFD, InputEvents, sizeof(InputEvents));
+                            if(BytesRead != -1)
+                            {
+                                for(int EventIndex = 0;
+                                    EventIndex < (int)ArrayCount(InputEvents);
+                                    EventIndex++)
+                                {
+                                    struct input_event EventAt = InputEvents[EventIndex];
+                                    
+                                    switch(EventAt.type)
+                                    {
+                                        case EV_KEY:
+                                        {
+                                            b32 IsDown = EventAt.value;
+                                            if(0) {}
+                                            else if(EventAt.code == BTN_A)
+                                            {
+                                                NewController->ActionDown.EndedDown = IsDown;
+                                            }
+                                            else if(EventAt.code == BTN_B)
+                                            {
+                                                NewController->ActionRight.EndedDown = IsDown;
+                                            }
+                                            else if(EventAt.code == BTN_X)
+                                            {
+                                                NewController->ActionLeft.EndedDown = IsDown;
+                                            }
+                                            else if(EventAt.code == BTN_Y)
+                                            {
+                                                NewController->ActionUp.EndedDown = IsDown;
+                                            }
+                                            else if(EventAt.code == BTN_START)
+                                            {
+                                                NewController->Start.EndedDown = IsDown;
+                                            }
+                                            else if(EventAt.code == BTN_BACK)
+                                            {
+                                                NewController->Back.EndedDown = IsDown;
+                                            }
+                                        } break;
+                                        
+                                        case EV_ABS:
+                                        {
+                                            if(0) {}
+                                            else if(EventAt.code == ABS_X)
+                                            {
+                                                NewController->IsAnalog = true;
+                                                
+                                                NewController->StickAverageX = LinuxNormalizeAxisValue(EventAt.value, GamePadAt->Axes[LSTICKX]);
+                                            }
+                                            else if(EventAt.code == ABS_Y)
+                                            {
+                                                NewController->StickAverageY = -1.0f * LinuxNormalizeAxisValue(EventAt.value, GamePadAt->Axes[LSTICKY]);
+                                            }
+                                            else if(EventAt.code == ABS_HAT0X)
+                                            {
+                                                NewController->StickAverageX = EventAt.value;
+                                                NewController->IsAnalog = false;
+                                            }
+                                            else if(EventAt.code == ABS_HAT0Y)
+                                            {
+                                                NewController->StickAverageY = -EventAt.value;
+                                                NewController->IsAnalog = false;
+                                            }
+                                        } break;
+                                    }
+#if 0
+                                    if(EventAt.type) printf("%d %d %d\n", EventAt.type, EventAt.code, EventAt.value);
+#endif
+                                }
+                                
+                            }
+                        }
+                    }
+                    
+                    
+                    // NOTE(luca): Buffer is cleared just in case.
+#if 1
+                    for(int X = 0; X < OffscreenBuffer.Width; X++)
+                    {
+                        for(int Y = 0; Y < OffscreenBuffer.Height; Y++)
+                        {
+                            ((u32 *)OffscreenBuffer.Memory)[X + Y*OffscreenBuffer.Width] = 0;
+                        }
+                    }
+#endif
+                    
+                    if(!GlobalPaused)
+                    {
+                        if(Game.UpdateAndRender)
+                        {
+                            Game.UpdateAndRender(&ThreadContext, &GameMemory, NewInput, &OffscreenBuffer);
+                        }
+                    }
+                    
+                    r32 SamplesToWrite = TargetSecondsPerFrame*SampleRate;
+                    local_persist b32 AudioFillFirstTime = true;
+                    r32 SecondsSinceFlip = (LinuxGetSecondsElapsed(FlipWallClock, LinuxGetWallClock()))/1000000000.0f;
+                    r32 SecondsLeftUntilFlip = TargetSecondsPerFrame - SecondsSinceFlip;
+                    if(AudioFillFirstTime)
+                    {
+                        SamplesToWrite += SecondsLeftUntilFlip*SampleRate;
+                        AudioFillFirstTime = false;
+                    }
+                    
+#if HANDMADE_INTERNAL                    
+                    snd_htimestamp_t AudioTimeStamp = {};
+                    snd_pcm_status(PCMHandle, PCMStatus);
+                    sound_status *PCMSoundStatus = (sound_status *)PCMStatus;
+                    u32 AvailableFrames = snd_pcm_status_get_avail(PCMStatus);
+                    s32 DelayFrames = snd_pcm_status_get_delay(PCMStatus);
+                    snd_pcm_status_get_htstamp(PCMStatus, &AudioTimeStamp);
+                    struct timespec AudioWallClock = LinuxGetWallClock();
+                    
+#if 0                    
+                    // TODO(luca): Why does this work?
+                    if(DelayFrames > SamplesToWrite && DelayFrames > 0)
+                    {
+                        SamplesToWrite -= (DelayFrames - SamplesToWrite);
+                        if(SamplesToWrite < 0)
+                        {
+                            SamplesToWrite = 0;
+                        }
+                    }
+#endif
+                    
+                    u32 PadY = 16;
+                    u32 LineHeight = 38;
+                    u32 X = 0; 
+                    u32 Y = 0;
+                    
+                    u32 MapIntoWidth = (OffscreenBuffer.Width);
+                    
+                    X = MapIntoWidth*(r32)((r32)SamplesToWrite/(r32)SampleRate);
+                    LinuxDebugVerticalLine(&OffscreenBuffer, X, Y*LineHeight + PadY, 0x0030FF00);
+                    
+                    X = MapIntoWidth*(r32)((r32)AvailableFrames/(r32)PCMBufferSize);
+                    LinuxDebugVerticalLine(&OffscreenBuffer, X, Y*LineHeight + PadY, 0x0030FF00);
+                    
+                    X = MapIntoWidth*(r32)((r32)DelayFrames/(r32)PCMBufferSize);
+                    LinuxDebugVerticalLine(&OffscreenBuffer, X, Y*LineHeight + PadY, 0x00FF00FF);
+                    
+                    Y++;
+                    
+                    X = MapIntoWidth*(r32)((r32)SecondsSinceFlip/TargetSecondsPerFrame);
+                    LinuxDebugVerticalLine(&OffscreenBuffer, X, Y*LineHeight + PadY, 0x0000FF00);
+                    
+#endif
+                    
+                    game_sound_output_buffer SoundBuffer = {};
+                    SoundBuffer.SamplesPerSecond = SampleRate;
+                    SoundBuffer.SampleCount = SamplesToWrite;
+                    SoundBuffer.Samples = (s16 *)AudioSamples;
+                    
+                    if(Game.GetSoundSamples)
+                    {
+                        Game.GetSoundSamples(&ThreadContext, &GameMemory, &SoundBuffer);
+                    }
+                    
+                    LastFramesWritten = snd_pcm_writei(PCMHandle, SoundBuffer.Samples, SoundBuffer.SampleCount);
+                    
+                    if(LastFramesWritten < 0)
+                    {
+                        // TODO(luca): Logging
+                        // NOTE(luca): We might want to silence in case of overruns ahead of time.  We also probably want to handle latency differently here. 
+                        snd_pcm_recover(PCMHandle, LastFramesWritten, 0);
+                    }
+                    
+                    printf("Expected: %d, Delay: %4d, Being written: %5lu, Written: %d, Ptr: %lu\n", 
+                           (int)SamplesToWrite, DelayFrames, PCMBufferSize - AvailableFrames, LastFramesWritten, PCMSoundStatus->hw_ptr);
+                    
+                    struct timespec WorkCounter = LinuxGetWallClock();
+                    r32 WorkSecondsElapsed = LinuxGetSecondsElapsed(LastCounter, WorkCounter);
+                    r32 SecondsElapsedForFrame = (WorkSecondsElapsed/1000000000.0f);
+                    if(SecondsElapsedForFrame < TargetSecondsPerFrame)
+                    {
+                        
+                        s64 SleepUS = (s64)((TargetSecondsPerFrame - 0.001 - SecondsElapsedForFrame)*1000000.0f);
+                        if(SleepUS > 0)
+                        {
+                            usleep(SleepUS);
+                        }
+                        else
+                        {
+                            // TODO(luca): Logging
+                        }
+                        
+                        r32 TestSecondsElapsedForFrame = (r32)(LinuxGetSecondsElapsed(LastCounter, LinuxGetWallClock()));
+                        if(TestSecondsElapsedForFrame < TargetSecondsPerFrame)
+                        {
+                            // TODO(luca): Log missed sleep
+                        }
+                        
+                        while(SecondsElapsedForFrame < TargetSecondsPerFrame)
+                        {
+                            SecondsElapsedForFrame = LinuxGetSecondsElapsed(LastCounter, LinuxGetWallClock())/1000000000.0f;
+                        }
+                    }
+                    else
+                    {
+                        // TODO(luca): Log missed frame rate!
+                    }
+                    
+                    struct timespec EndCounter = LinuxGetWallClock();
+                    r32 MSPerFrame = (r32)(LinuxGetSecondsElapsed(LastCounter, EndCounter)/1000000.f);
+                    LastCounter = EndCounter;
+                    
+                    XPutImage(DisplayHandle, WindowHandle, DefaultGC, WindowBuffer, 0, 0, 0, 0, Width, Height);
+                    FlipWallClock = LinuxGetWallClock();
+                    
+                    game_input *TempInput = NewInput;
+                    NewInput = OldInput;
+                    TempInput = NewInput;
+                    
+#if 0                    
+                    u64 EndCycleCount = __rdtsc();
+                    u64 CyclesElapsed = EndCycleCount - LastCycleCount;
+                    LastCycleCount = EndCycleCount;
+                    
+                    r64 FPS = 0;
+                    r64 MCPF = (r64)(CyclesElapsed/(1000.0f*1000.0f));
+                    printf("%.2fms/f %.2ff/s %.2fmc/f\n", MSPerFrame, FPS, MCPF);
+#endif
+                    
+                }
+                
+            }
+            else
+            {
+                // TODO: Log this bad WindowHandle
+            }
+        }
+        else
+        {
+            // TODO: Log this could not match visual info
+        }
+    }
+    else
+    {
+        // TODO: Log could not get x connection 
+    }
+    return 0;
+}