sound_test.c

#include <inttypes.h>
#include <gba_console.h>
#include <gba_video.h>
#include <gba_interrupt.h>
#include <gba_systemcalls.h>
#include <gba_input.h>
#include <gba_sound.h>
#include <gba_timers.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>



int main(void)
{
	// the vblank interrupt must be enabled for VBlankIntrWait() to work
	// since the default dispatcher handles the bios flags no vblank handler
	// is required
	irqInit();
	irqEnable(IRQ_VBLANK);

	consoleDemoInit();

	REG_SOUNDCNT_X = 1u<<7;
	REG_SOUNDCNT_H = 2u;
	REG_SOUNDCNT_L = 1u<<12 | 1u<<8 | 7u<<4 | 7u;
	SNDBIAS = 3u<<14 | 0x200u;
	REG_SOUND1CNT_L = 0;
	REG_SOUND1CNT_H = 15u<<12 | 2u<<6;
	REG_SOUND1CNT_X = 1u<<15; // start
	u16 freq = 1000;
	bool freqChanged = true;
	while(1)
	{
		const u16 kHeld = REG_KEYINPUT ^ 0xFFFFu;
		if(kHeld & KEY_UP) {freq++; freqChanged = true;}
		else if(kHeld & KEY_DOWN) {freq--; freqChanged = true;}

		if(freqChanged)
		{
			freqChanged = false;

			REG_SOUND1CNT_X = 2048 - (131072 / freq);
			iprintf("\rFreq: %05" PRIu16, freq);
		}

		VBlankIntrWait();
	}
}