ov518_decomp.c

是一个linux下的摄像头驱动,网上的驱动源码比较难找,这个基本能用,根据具体的摄像头配置和设置改下,linux下可编译

			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;
	out[4]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3 - tmp1 + tmp2) >> 17;
	out[27]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3 - C16 - C20) >> 17;
	out[28]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

// Second half
	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];

// 8,15,16,23

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

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

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

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

	t=(base + val1 + val2 + val3) >> 17;
	out[8]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3 - C4 + C16 + C20) >> 17;
	out[15]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3) >> 17;
	out[16]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3 - C4 + C20) >> 17;
	out[23]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

//9,14,17,22

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

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

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

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

	t=(base + val1 + val2 + val3 + C4 + C16 - C20) >> 17;
	out[9]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3 + C16) >> 17;
	out[14]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3 + C4) >> 17;
	out[17]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3) >> 17;
	out[22]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

//10,13,18,21

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

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

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

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

	t=(base + val1 + val2 + val3) >> 17;
	out[10]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3 + C4 + C16 - C20) >> 17;
	out[13]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 + val2 - val3) >> 17;
	out[18]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base + val1 - val2 - val3 + C4) >> 17;
	out[21]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;

// 11,12,19,20

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

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

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

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

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

	t=(base + val1 + val2 + val3 - tmp1 + tmp2 + C16 + C20) >> 17;
	out[11]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;
	t=(base - val1 - val2 + val3 + C16 + C20) >> 17;
	out[12]= t&0xFFFFFF00? t<0?0:255 : (unsigned char)t;