ov518_decomp.c

支持linux2.6和linux2.4的ov511摄像头驱动源码

		depth = tree[node].depth;

		/* Is it a leaf? If not, branch downward */
		if (depth != -1) {
			*coeffbits = tree[node].coeffbits;
			*skip = tree[node].skip;
			return depth;
		}

		in <<= 1;
		++i;
	} while (i <= 15);

	return -1;
}

/* If no node is found, coeffbits will not be modified */
/* Return: Depth of node found, or -1 if invalid input code */
static int 
getNodeDC(unsigned int in, signed char *coeffbits, const struct tree_node *tree)
{
	int node = 0;
	int i = 0;
	int depth;

	do {
		if ((in & 0x80000000) == 0)
			node = tree[node].left;
		else
			node = tree[node].right;

		if (node == -1)
			break;

		depth = tree[node].depth;

		/* Is it a leaf? If not, branch downward */
		if (depth != -1) {
			*coeffbits = tree[node].coeffbits;
			return depth;
		}

		in <<= 1;
		++i;
	} while (i <= 15);

	return -1;
}

static inline unsigned int 
getBytes(int *rawData, struct comp_info *cinfo)
{
	int bufLen = cinfo->rawLen;
	int bits = cinfo->bits;
	int bytes = cinfo->bytes;
	unsigned char *in = bytes + (unsigned char *) rawData;
	unsigned char b1, b2, b3, b4, b5;
	unsigned int packedIn;

	/* Pull 5 bytes out of raw data */
	if (bytes < bufLen - 4) {
		b1 = in[0];
		b2 = in[1];
		b3 = in[2];
		b4 = in[3];
		b5 = in[4];
	} else {
		if (bytes < bufLen - 3) {
			b1 = in[0];
			b2 = in[1];
			b3 = in[2];
			b4 = in[3];
		} else {
			if (bytes < bufLen - 2) {
				b1 = in[0];
				b2 = in[1];
				b3 = in[2];
			} else {
				if (bytes < bufLen - 1) {
					b1 = in[0];
					b2 = in[1];
				} else {
					if (bytes <= bufLen) {
						b1 = in[0];
					} else {
						b1 = 0;
					}
					b2 = 0;
				}
				b3 = 0;
			}
			b4 = 0;
		}
		b5 = 0;
	}

	/* Pack the bytes */
	packedIn  = b1 << 24;
	packedIn += b2 << 16;
	packedIn += b3 << 8;
	packedIn += b4;

	if (bits != 0) {
		packedIn = packedIn << bits;
		packedIn += b5 >> (8 - bits);
	}

	return packedIn;
}

static int 
getACCoefficient(int *rawData, int *coeff, struct comp_info *cinfo,
		 const struct tree_node *tree)
{
	int input, bits, bytes, tmp_c;
	signed char coeffbits = 0;
	signed char skip = 0;

	input = getBytes(rawData, cinfo);
	bits = getNodeAC(input, &coeffbits, &skip, tree);

	if (coeffbits) {
		input = input << (bits - 1);
		input &= 0x7fffffff;
		if (! (input & 0x40000000))
			input |= 0x80000000;

		tmp_c = input >> (31 - coeffbits);
		if (tmp_c < 0)
			tmp_c++;
		*coeff = tmp_c;

		bits += coeffbits;
	}

	bytes = (bits + cinfo->bits) >> 3;
	cinfo->bytes += bytes;
	cinfo->bits += bits - (bytes << 3);

	return skip;
}

static void 
getDCCoefficient(int *rawData, int *coeff, struct comp_info *cinfo,
		 const struct tree_node *tree)
{
	int input, bits, bytes, tmp_c;
	signed char coeffbits = 0;

	input = getBytes(rawData, cinfo);
	bits = getNodeDC(input, &coeffbits, tree);

	if (bits == -1) {
		bits = 1;	/* Try to re-sync at the next bit */
		*coeff = 0;	/* Indicates no change from last DC */
	} else {

		input = input << (bits - 1);
		input &= 0x7fffffff;
		if (! (input & 0x40000000))
			input |= 0x80000000;

		tmp_c = input >> (31 - coeffbits);
		if (tmp_c < 0)
			tmp_c++;
		*coeff = tmp_c;

		bits += coeffbits;
	}

	bytes = (bits + cinfo->bits) >> 3;
	cinfo->bytes += bytes;
	cinfo->bits += bits - (bytes << 3);
}

/* For AC coefficients, here is what the "skip" value means:
 *   -1: Either the 8x4 block has ended, or the decoding failed.
 *    0: Use the returned coeff. Don't skip anything.
 * 1-15: The next <skip> coeffs are zero. The returned coeff is used.
 *   16: The next 16 coeffs are zero. The returned coeff is ignored.
 *
 * You must ensure that the C[] array not be overrun, or stack corruption will
 * result.
 */
static void 
huffmanDecoderY(int *C, int *pIn, struct comp_info *cinfo)
{
	int coeff = 0;
	int i = 1;
	int k, skip;

	getDCCoefficient(pIn, C, cinfo, treeYDC);

	i = 1;
	do {
		skip = getACCoefficient(pIn, &coeff, cinfo, treeYAC);

		if (skip == -1) {
			break;
		} else if (skip == 0) {
			C[i++] = coeff;
		} else if (skip == 16) {
			k = 16;
			if (i > 16)
				k = 32 - i;

			while (k--)
				C[i++] = 0;
		} else {
			k = skip;
			if (skip > 31 - i)
				k = 31 - i;

			while (k--)
				C[i++] = 0;

			C[i++] = coeff;
		}
	} while (i <= 31);

	if (skip == -1)
		while (i <= 31)  C[i++] = 0;
	else
		getACCoefficient(pIn, &coeff, cinfo, treeYAC);
}

/* Same as huffmanDecoderY, except for the tables used */
static void 
huffmanDecoderUV(int *C, int *pIn, struct comp_info *cinfo)
{
	int coeff = 0;
	int i = 1;
	int k, skip;

	getDCCoefficient(pIn, C, cinfo, treeUVDC);

	i = 1;
	do {
		skip = getACCoefficient(pIn, &coeff, cinfo, treeUVAC);

		if (skip == -1) {
			break;
		} else if (skip == 0) {
			C[i++] = coeff;
		} else if (skip == 16) {
			k = 16;
			if (i > 16)
				k = 32 - i;

			while (k--)
				C[i++] = 0;
		} else {
			k = skip;
			if (skip > 31 - i)
				k = 31 - i;

			while (k--)
				C[i++] = 0;

			C[i++] = coeff;
		}
	} while (i <= 31);

	if (skip == -1)
		while (i <= 31)  C[i++] = 0;
	else
		getACCoefficient(pIn, &coeff, cinfo, treeUVAC);
}

/******************************************************************************
 * iDCT Functions
 ******************************************************************************/

#ifndef APPROXIMATE_MUL_BY_SHIFT

#define IDCT_MESSAGE "iDCT with multiply"

#define TIMES_16382(u)	((u)? 16382 * (u):0)
#define TIMES_23168(u)	((u)? 23168 * (u):0)
#define TIMES_30270(u)	((u)? 30270 * (u):0)
#define TIMES_41986(u)	((u)? 41986 * (u):0)
#define TIMES_35594(u)	((u)? 35594 * (u):0)
#define TIMES_23783(u)	((u)? 23783 * (u):0)
#define TIMES_8351(u)	((u)? 8351  * (u):0)
#define TIMES_17391(u)	((u)? 17391 * (u):0)
#define TIMES_14743(u)	((u)? 14743 * (u):0)
#define TIMES_9851(u)	((u)? 9851  * (u):0)
#define TIMES_3459(u)	((u)? 3459  * (u):0)
#define TIMES_32134(u)	((u)? 32134 * (u):0)
#define TIMES_27242(u)	((u)? 27242 * (u):0)
#define TIMES_18202(u)	((u)? 18202 * (u):0)
#define TIMES_6392(u)	((u)? 6392  * (u):0)
#define TIMES_39550(u)	((u)? 39550 * (u):0)
#define TIMES_6785(u)	((u)? 6785  * (u):0)
#define TIMES_12538(u)	((u)? 12538 * (u):0)

#else

#define IDCT_MESSAGE "iDCT with shift"

#define TIMES_16382(u) ( (u)? x=(u) , (x<<14) - (x<<1) :0 )
#define TIMES_23168(u) ( (u)? x=(u) , (x<<14) + (x<<12) + (x<<11) + (x<<9) :0 )
#define TIMES_30270(u) ( (u)? x=(u) , (x<<15) - (x<<11) :0 )
#define TIMES_41986(u) ( (u)? x=(u) , (x<<15) + (x<<13) + (x<<10) :0 )
#define TIMES_35594(u) ( (u)? x=(u) , (x<<15) + (x<<11) + (x<<9) + (x<<8) :0 )
#define TIMES_23783(u) ( (u)? x=(u) , (x<<14) + (x<<13) - (x<<9) - (x<<8) :0 )
#define TIMES_8351(u)  ( (u)? x=(u) , (x<<13) :0 )
#define TIMES_17391(u) ( (u)? x=(u) , (x<<14) + (x<<10) :0 )
#define TIMES_14743(u) ( (u)? x=(u) , (x<<14) - (x<<10) - (x<<9) :0 )
#define TIMES_9851(u)  ( (u)? x=(u) , (x<<13) + (x<<10) + (x<<9) :0 )
#define TIMES_3459(u)  ( (u)? x=(u) , (x<<12) - (x<<9) :0 )
#define TIMES_32134(u) ( (u)? x=(u) , (x<<15) - (x<<9) :0 )
#define TIMES_27242(u) ( (u)? x=(u) , (x<<14) + (x<<13) + (x<<11) + (x<<9) :0 )
#define TIMES_18202(u) ( (u)? x=(u) , (x<<14) + (x<<11) - (x<<8) :0 )
#define TIMES_6392(u)  ( (u)? x=(u) , (x<<13) - (x<<11) + (x<<8) :0 )
#define TIMES_39550(u) ( (u)? x=(u) , (x<<15) + (x<<12) + (x<<11) + (x<<9) :0 )
#define TIMES_6785(u)  ( (u)? x=(u) , (x<<12) + (x<<11) + (x<<9) :0 )
#define TIMES_12538(u) ( (u)? x=(u) , (x<<13) + (x<<12) + (x<<8) :0 )

/*
 * The variables C0, C4, C16 and C20 can also be removed from the algorithm
 * if APPROXIMATE_MUL_BY_SHIFTS is defined. They store correction values
 * and can be considered insignificant.
 */

#endif

static void 
DCT_8x4(int *coeff, unsigned char *out)
/* pre: coeff == coefficients
   post: coeff != coefficients
   ** DO NOT ASSUME coeff TO BE THE SAME BEFORE AND AFTER CALLING THIS FUNCTION!
*/
{
	register int base,val1,val2,val3;
	int tmp1,tmp2;
	int C0,C4,C16,C20;
	int C2_18,C6_22,C1_17,C3_19,C5_21,C7_23;
	register int t;
#ifdef APPROXIMATE_MUL_BY_SHIFT
	register int x;
#endif

	C0=coeff[0];
	C4=coeff[4];
	C16=coeff[16];
	C20=coeff[20];

	coeff[0]=TIMES_23168(coeff[0]);
	coeff[4]=TIMES_23168(coeff[4]);
	coeff[16]=TIMES_23168(coeff[16]);
	coeff[20]=TIMES_23168(coeff[20]);

	C2_18 = coeff[2]+coeff[18];
	C6_22 = coeff[6]+coeff[22];
	C1_17 = coeff[1]+coeff[17];
	C3_19 = coeff[3]+coeff[19];
	C5_21 = coeff[5]+coeff[21];
	C7_23 = coeff[7]+coeff[23];

// 0,7,25,32

	base = 0x1000000;
	base += coeff[0]+coeff[4]+coeff[16]+coeff[20];
	base += TIMES_30270(C2_18);
	base += TIMES_12538(C6_22);

	val1 = TIMES_41986(coeff[9]);
	val1 += TIMES_35594(coeff[11]);
	val1 += TIMES_23783(coeff[13]);
	val1 += TIMES_8351(coeff[15]);
	val1 += TIMES_17391(coeff[25]);
	val1 += TIMES_14743(coeff[27]);
	val1 += TIMES_9851(coeff[29]);
	val1 += TIMES_3459(coeff[31]);

	val2 = TIMES_32134(C1_17);
	val2 += TIMES_27242(C3_19);
	val2 += TIMES_18202(C5_21);
	val2 += TIMES_6392(C7_23);

	val3 = TIMES_39550(coeff[10]);
	val3 += TIMES_16382(coeff[14]+coeff[26]);
	val3 += TIMES_6785(coeff[30]);
	val3 += TIMES_30270(coeff[8]+coeff[12]);
	val3 += TIMES_12538(coeff[24]+coeff[28]);

	t=(base + val1 + val2 + val3) >> 17;
	out[0]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3 - C4 - C20) >> 17;
	out[7]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3 - C16- C20) >> 17;
	out[24]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3 - C4 - C16 - C20) >> 17;
	out[31]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

//1,6,25,30

	base = 0x1000000;
	base += coeff[0]-coeff[4]+coeff[16]-coeff[20];
	base += TIMES_12538(C2_18);
	base -= TIMES_30270(C6_22);

	val1 = TIMES_35594(coeff[9]);
	val1 -= TIMES_8351(coeff[11]);
	val1 -= TIMES_41986(coeff[13]);
	val1 -= TIMES_23783(coeff[15]);
	val1 -= TIMES_14743(coeff[25]);
	val1 -= TIMES_3459(coeff[27]);
	val1 -= TIMES_17391(coeff[29]);
	val1 -= TIMES_9851(coeff[31]);

	val2 = TIMES_27242(C1_17);
	val2 -= TIMES_6392(C3_19);
	val2 -= TIMES_32134(C5_21);
	val2 -= TIMES_18202(C7_23);

	val3 = TIMES_16382(coeff[10]-coeff[30]);
	val3 -= TIMES_39550(coeff[14]);
	val3 += TIMES_6785(coeff[26]);
	val3 += TIMES_12538(coeff[24]-coeff[28]);
	val3 += TIMES_30270(coeff[8]-coeff[12]);

	t=(base + val1 + val2 + val3 + C4 + C20) >> 17;
	out[1]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3) >> 17;
	out[6]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3 + C4 - C16 + C20) >> 17;
	out[25]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3 + C20) >> 17;
	out[30]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

//2,5,26,29

	base = 0x1000000;
	base += coeff[0] - coeff[4] + coeff[16] - coeff[20];
	base -= TIMES_12538(C2_18);
	base += TIMES_30270(C6_22);

	val1 = TIMES_23783(coeff[9]);
	val1 -= TIMES_41986(coeff[11]);
	val1 += TIMES_8351(coeff[13]);
	val1 += TIMES_35594(coeff[15]);
	val1 += TIMES_9851(coeff[25]);
	val1 -= TIMES_17391(coeff[27]);
	val1 += TIMES_3459(coeff[29]);
	val1 += TIMES_14743(coeff[31]);

	val2 = TIMES_18202(C1_17);
	val2 -= TIMES_32134(C3_19);
	val2 += TIMES_6392(C5_21);
	val2 += TIMES_27242(C7_23);

	val3 = -TIMES_16382(coeff[10] - coeff[30]);
	val3 += TIMES_39550(coeff[14]);
	val3 -= TIMES_6785(coeff[26]);
	val3 += TIMES_12538(coeff[24] - coeff[28]);
	val3 += TIMES_30270(coeff[8] - coeff[12]);

	t=(base + val1 + val2 + val3) >> 17;
	out[2]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3) >> 17;
	out[5]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3 - C16) >> 17;
	out[26]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3 + C4 - C16 + C20) >> 17;
	out[29]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

//3,4,27,28

	base = 0x1000000;
	base += coeff[0] + coeff[4] + coeff[16] + coeff[20];
	base -= TIMES_30270(C2_18);
	base -= TIMES_12538(C6_22);

	val1 = TIMES_8351(coeff[9]);
	val1 -= TIMES_23783(coeff[11]);
	val1 += TIMES_35594(coeff[13]);
	val1 += TIMES_3459(coeff[25]);
	val1 -= TIMES_9851(coeff[27]);
	val1 += TIMES_14743(coeff[29]);

	val2 = TIMES_6392(C1_17);
	val2 -= TIMES_18202(C3_19);
	val2 += TIMES_27242(C5_21);

	val3 = -TIMES_39550(coeff[10]);
	val3 += TIMES_16382(coeff[14] + coeff[26]);
	val3 -= TIMES_6785(coeff[30]);
	val3 += TIMES_30270(coeff[8] + coeff[12]);
	val3 += TIMES_12538(coeff[24] + coeff[28]);

	tmp1 = TIMES_32134(C7_23);
	tmp2 = TIMES_41986(coeff[15]) + TIMES_17391(coeff[31]);

	t=(base + val1 + val2 + val3 - tmp1 - tmp2 - C4 - C20) >> 17;
	out[3]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3) >> 17;