g711.c

zigbee 飞思卡尔 音频传输 基于ucos的所有源码

#define	SIGN_BIT	(0x80)		/* Sign bit for a A-law byte. */
#define	QUANT_MASK	(0xf)		/* Quantization field mask. */
#define	NSEGS		(8)		/* Number of A-law segments. */
#define	SEG_SHIFT	(4)		/* Left shift for segment number. */
#define	SEG_MASK	(0x70)		/* Segment field mask. */

static int seg_aend[8] = {0x1F, 0x3F, 0x7F, 0xFF,
			    0x1FF, 0x3FF, 0x7FF, 0xFFF};
static int
search(
	int		val,	/* changed from "short" *drago* */
	int *	table,
	int		size)	/* changed from "short" *drago* */
{
	int		i;		/* changed from "short" *drago* */

	for (i = 0; i < size; i++) {
		if (val <= *table++)
			return (i);
	}
	return (size);
}


int linear2alaw(int	pcm_val)        /* 2's complement (16-bit range) */
                                        /* changed from "short" *drago* */
{
	int		mask;	/* changed from "short" *drago* */
	int		seg;	/* changed from "short" *drago* */
	int		aval;

	pcm_val = pcm_val >> 3;

	if (pcm_val >= 0) {
		mask = 0xD5;		/* sign (7th) bit = 1 */
	} else {
		mask = 0x55;		/* sign bit = 0 */
		pcm_val = -pcm_val - 1;
	}

	/* Convert the scaled magnitude to segment number. */
	seg = search(pcm_val, seg_aend, 8);

	/* Combine the sign, segment, and quantization bits. */

	if (seg >= 8)		/* out of range, return maximum value. */
		return (0x7F ^ mask);
	else {
		aval = seg << SEG_SHIFT;
		if (seg < 2)
			aval |= (pcm_val >> 1) & QUANT_MASK;
		else
			aval |= (pcm_val >> seg) & QUANT_MASK;
		return (aval ^ mask);
	}
}


int alaw2linear(int	a_val)		
{
	int		t;      /* changed from "short" *drago* */
	int		seg;    /* changed from "short" *drago* */

	a_val ^= 0x55;

	t = (a_val & QUANT_MASK) << 4;
	seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT;
	switch (seg) {
	case 0:
		t += 8;
		break;
	case 1:
		t += 0x108;
		break;
	default:
		t += 0x108;
		t <<= seg - 1;
	}
	return ((a_val & SIGN_BIT) ? t : -t);
}
int g711modle(int data)
{
	int a_lawd;
	int a_lawo;
	a_lawd = linear2alaw(data);
	a_lawo = alaw2linear(a_lawd);
	return a_lawo;
}