dct.h

ARM嵌入式常用模块的原理图和源码

#include "DataType.h"
void ffdct(LINT8 *mcubyte, LINT32 *array)
{
	LINT32 tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
	LINT32 tmp10, tmp11, tmp12, tmp13;
	LINT32 z1, z2, z3, z4, z5, z11, z13;
	LINT32* dataptr;
	LINT8* datain;
	int ctr;
	datain = mcubyte;
	dataptr = array;
	for(ctr=0;ctr<64;ctr++)
	{
		dataptr[ctr]=datain[ctr]-128;
	}
												/* 第一部分，对行进行计算 */
	for (ctr = 7; ctr >= 0; ctr--)
	{
		tmp0 = dataptr[0] + dataptr[7];
		tmp7 = dataptr[0] - dataptr[7];
		tmp1 = dataptr[1] + dataptr[6];
		tmp6 = dataptr[1] - dataptr[6];
		tmp2 = dataptr[2] + dataptr[5];
		tmp5 = dataptr[2] - dataptr[5];
		tmp3 = dataptr[3] + dataptr[4];
		tmp4 = dataptr[3] - dataptr[4];
												/* 对偶数项进行运算 */
		tmp10 = tmp0 + tmp3;                /* 相位2 */
		tmp13 = tmp0 - tmp3;
		tmp11 = tmp1 + tmp2;
		tmp12 = tmp1 - tmp2;
		dataptr[0] = tmp10 + tmp11;         /*相位3 */
		dataptr[4] = tmp10 - tmp11;
		z1 = (tmp12 + tmp13) * (46341);    /* c4 / 0.707106781 */
		z1 = z1 >> 16;
		dataptr[2] = tmp13 + z1;            /* 相位 5 */
		dataptr[6] = tmp13 - z1;
												   /* 对奇数项进行计算 */
		tmp10 = tmp4 + tmp5;                  /* 相位2 */
		tmp11 = tmp5 + tmp6;
		tmp12 = tmp6 + tmp7;
		z5 = (tmp10 - tmp12) * (25080);      /* c6 /0.382683433 */
		z5 = z5 >> 16;

		z2 = tmp10*(35468);
		z2 = z2 >> 16;
		z2 = z2 + z5;

		z4 = tmp12 * (85627);
		z4 = z4 >> 16;
		z4 = z4 + z5;
		z3 = tmp11 * (46341);                /* c4 / 0.707106781*/
		z3 = z3 >> 16;
		z11 = tmp7 + z3; 					/* 相位 5 */
		z13 = tmp7 - z3;
		dataptr[5] = z13 + z2; 				/* 相位 6 */
		dataptr[3] = z13 - z2;
		dataptr[1] = z11 + z4;
		dataptr[7] = z11 - z4;
		dataptr += 8;							/* 将指针指向下一行 */
	}
												/* 第二部分，对列进行计算 */
	dataptr = array;
	for (ctr = 7; ctr >= 0; ctr--)
	{
		tmp0 = dataptr[0] + dataptr[56];
		tmp7 = dataptr[0] - dataptr[56];
		tmp1 = dataptr[8] + dataptr[48];
		tmp6 = dataptr[8] - dataptr[48];
		tmp2 = dataptr[16] + dataptr[40];
		tmp5 = dataptr[16] - dataptr[40];
		tmp3 = dataptr[24] + dataptr[32];
		tmp4 = dataptr[24] - dataptr[32];
													/* 对偶数项进行运算 */
		tmp10 = tmp0 + tmp3;		 			/* 相位 2 */
		tmp13 = tmp0 - tmp3;
		tmp11 = tmp1 + tmp2;
		tmp12 = tmp1 - tmp2;
		dataptr[0] = tmp10 + tmp11; 			/* 相位3 */
		dataptr[32] = tmp10 - tmp11;
		z1 = (tmp12 + tmp13) * (46341); 		/* c4 / 0.707106781 */
		z1 = z1 >> 16;
		dataptr[16] = tmp13 + z1; 			/* 相位5 */
		dataptr[48] = tmp13 - z1;
													/* 对奇数项进行计算 */
		tmp10 = tmp4 + tmp5; 					/* phase 2 */
		tmp11 = tmp5 + tmp6;
		tmp12 = tmp6 + tmp7;
		z5 = (tmp10 - tmp12) * (25080);		 /* c6 /0.382683433 */
		z5 = z5 >> 16;
		z2 = tmp10*(35468);
		z2 = z2 >> 16;
		z2 = z2 + z5;
		z4 = tmp12 * (85627);
		z4 = z4 >> 16;
		z4 = z4 + z5;
		z3 = tmp11 * (46341); 					/* c4 / 0.707106781*/
		z3 = z3 >> 16;
		z11 = tmp7 + z3; 						/* 相位5 */
		z13 = tmp7 - z3;
		dataptr[40] = z13 + z2; 				/* 相位6 */
		dataptr[24] = z13 - z2;
		dataptr[8] = z11 + z4;
		dataptr[56] = z11 - z4;
		++dataptr; 								/* 将指针指向下一列 */
	}
	dataptr = array;
	for(ctr=0;ctr<64;ctr++) dataptr[ctr]=dataptr[ctr]>>3;}