main.c

来自「psp游戏机上的SDK的开发例子」· C语言 代码 · 共 201 行

/* 
   AudioLib Sample

   Demonstrates how to get sound working with minimal effort.

   Based on sdktest sample from pspsdk
*/

#include <pspkernel.h>
#include <pspdebug.h>
#include <pspaudiolib.h>
#include <pspaudio.h>
#include <pspdisplay.h>
#include <pspctrl.h>

#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>

/* 
   This part of the code is more or less identical to the sdktest sample 
*/

/* Define the module info section */
PSP_MODULE_INFO("AUDIOLIBDEMO", 0, 1, 1);
/* Define the main thread's attribute value (optional) */
PSP_MAIN_THREAD_ATTR(THREAD_ATTR_USER | THREAD_ATTR_VFPU);
/* Define printf, just to make typing easier */
#define printf	pspDebugScreenPrintf

/* Exit callback */
int exitCallback(int arg1, int arg2, void *common) {
	sceKernelExitGame();
	return 0;
}

/* Callback thread */
int callbackThread(SceSize args, void *argp) {
	int cbid;

	cbid = sceKernelCreateCallback("Exit Callback", (void*) exitCallback, NULL);
	sceKernelRegisterExitCallback(cbid);
	sceKernelSleepThreadCB();

	return 0;
}

/* Sets up the callback thread and returns its thread id */
int setupCallbacks(void) {
	int thid = 0;

	thid = sceKernelCreateThread("update_thread", callbackThread, 0x11, 0xFA0, 0, 0);
	if (thid >= 0) {
		sceKernelStartThread(thid, 0, 0);
	}
	return thid;
}

/*
  Below this point is the interesting code in this sample
*/

const float PI = 3.1415926535897932f;
const int sampleRate = 44100;
float frequency = 440.0f;
float time = 0;
int function = 0;

typedef struct {
        short l, r;
} sample_t;

float currentFunction(const float time) {
        double x;
	float t = modf(time / (2 * PI), &x);

        switch(function) {
	case 0: // SINE
	        return sinf(time);
	case 1: // SQUARE
	        if (t < 0.5f) {
	                return -0.2f;
	        } else {
	                return 0.2f;
	        }
	case 2: // TRIANGLE
	        if (t < 0.5f) {
	                return t * 2.0f - 0.5f;
	        } else {
	                return 0.5f - (t - 0.5f) * 2.0f;
	        }
	default:
 	        return 0.0f;
        }
}


/* This function gets called by pspaudiolib every time the
   audio buffer needs to be filled. The sample format is
   16-bit, stereo. */
void audioCallback(void* buf, unsigned int length, void *userdata) {
        const float sampleLength = 1.0f / sampleRate;
	const float scaleFactor = SHRT_MAX - 1.0f;
        static float freq0 = 440.0f;
       	sample_t* ubuf = (sample_t*) buf;
	int i;
	
	if (frequency != freq0) {
	        time *= (freq0 / frequency);
	}
	for (i = 0; i < length; i++) {
	        short s = (short) (scaleFactor * currentFunction(2.0f * PI * frequency * time));
		ubuf[i].l = s;
		ubuf[i].r = s;
		time += sampleLength;
	}
	if (time * frequency > 1.0f) {
	        double d;
		time = modf(time * frequency, &d) / frequency;
	}
	freq0 = frequency;
}

/* Read the analog stick and adjust the frequency */
void controlFrequency() {
        static int oldButtons = 0;
	const int zones[6] = {30, 70, 100, 112, 125, 130};
	const float response[6] = {0.0f, 0.1f, 0.5f, 1.0f, 4.0f, 8.0f};
	const float minFreq = 32.0f;
	const float maxFreq = 7040.0f;
	SceCtrlData pad;
	float direction;
	int changedButtons;
	int i, v;

	sceCtrlReadBufferPositive(&pad, 1);

	v = pad.Ly - 128;
	if (v < 0) {
   	        direction = 1.0f;
		v = -v;
	} else {
	        direction = -1.0f;
	}

	for (i = 0; i < 6; i++) {
	        if (v < zones[i]) {
		          frequency += response[i] * direction;
			  break;
	        }
	}

	if (frequency < minFreq) {
	        frequency = minFreq;
	} else if (frequency > maxFreq) {
	        frequency = maxFreq;
	}

	changedButtons = pad.Buttons & (~oldButtons);
	if (changedButtons & PSP_CTRL_CROSS) {
	        function++;
	        if (function > 2) {
	                 function = 0;
	        }
	}
	oldButtons = pad.Buttons;
}

int main(void) {
	pspDebugScreenInit();
	setupCallbacks();

	pspAudioInit();
	pspAudioSetChannelCallback(0, audioCallback, NULL);

	sceCtrlSetSamplingCycle(0);
	sceCtrlSetSamplingMode(PSP_CTRL_MODE_ANALOG);

	printf("Press up and down to select frequency\nPress X to change function\n");
	
	while(1) {
		sceDisplayWaitVblankStart();
		pspDebugScreenSetXY(0,2);
		printf("freq = %.2f   \n", frequency);
		switch(function) {
		case 0:
		  printf("sine wave\n");
		  break;
		case 1:
		  printf("square wave\n");
		  break;
		case 2:
		  printf("triangle wave\n");
		  break;
		}
		controlFrequency();
	}
	return 0;
}