lemur/game.c

#include <audio.h>
#include <assets.h>
#include <controller.h>
#include <game.h>
#include <SDL2/SDL.h>
#include <stdbool.h>
#include <time.h>

int sleepNanos(long int ns) {
    struct timespec time;
    if (ns < 0) return 0;
    time.tv_sec = ns / 1000000000;
    time.tv_nsec = ns % 1000000000;
    return nanosleep(&time, NULL);
}
long int tickNs() {
    struct timespec time;
    clock_gettime(CLOCK_MONOTONIC, &time);
    return (time.tv_sec * 1000000000) + time.tv_nsec;
}

typedef struct {
    GraphicsContext *gfx;
    AudioContext aud;
    int16_t audioBuffer[834 * 2];
} GameState;

int onFrame(VB *sim) {
    static uint8_t leftEye[384*224];
    static uint8_t rightEye[384*224];
    GameState *state;
    void *samples;
    uint32_t samplePairs;

    state = vbGetUserData(sim);
    
    vbGetPixels(sim, leftEye, 1, 384, rightEye, 1, 384);
    gfxUpdateLeftEye(state->gfx, leftEye);
    gfxUpdateRightEye(state->gfx, rightEye);

    samples = vbGetSamples(sim, NULL, &samplePairs);
    audioUpdate(&state->aud, samples, samplePairs * 4);
    vbSetSamples(sim, samples, 834);
    gfxRender(state->gfx);
    return 1;
}

#define MAX_STEP_CLOCKS 20000000

int runGame(VB *sim, GraphicsContext *gfx) {
    uint32_t clocks;
    SDL_Event event;
    GameState state;
    ControllerState ctrl;
    uint64_t ticks, prevTicks;

    state.gfx = gfx;
    audioInit(&state.aud);
    vbSetSamples(sim, &state.audioBuffer, 834);
    vbSetUserData(sim, &state);
    vbSetFrameCallback(sim, &onFrame);

    ctrlInit(&ctrl);

    gfxUpdateLeftEye(gfx, LEFT_EYE_DEFAULT);
    gfxUpdateRightEye(gfx, RIGHT_EYE_DEFAULT);

    while (1) {
        clocks = MAX_STEP_CLOCKS;
        prevTicks = tickNs();
        vbEmulate(sim, &clocks);
        ticks = tickNs();
        sleepNanos(((MAX_STEP_CLOCKS - clocks) * 50) - (ticks - prevTicks));

        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                return 0;
            }
            if (event.type == SDL_KEYDOWN) {
                ctrlKeyDown(&ctrl, event.key.keysym.sym);
            }
            if (event.type == SDL_KEYUP) {
                ctrlKeyUp(&ctrl, event.key.keysym.sym);
            }
        }
        vbSetKeys(sim, ctrlKeys(&ctrl));
    }
}