filter.c sobel filter code for MXP

filter.c

#include "vbx.h"

void filter(uint8_t* in_vid,uint8_t* out_vid,int rows, int cols,int pitch){
	int rowlen=cols;
	// save scratchpad allocator state
	vbx_sp_push();
	vbx_ubyte_t* line_in= vbx_sp_malloc(rowlen*3);

	vbx_word_t* v_tmp0=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* v_tmp1=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* v_tmp2=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* luma_top=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* luma_mid=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* luma_bot=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* sobel_top=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* sobel_mid=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* sobel_bot=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* grad_x=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));
	vbx_word_t* grad_y=vbx_sp_malloc(rowlen*sizeof(vbx_word_t));


	int row;
	for(row=0;row<rows;row++){
		//load a row into scratchpad
		vbx_dma_to_vector(line_in,in_vid+row*pitch*3,rowlen*3);

		//extract each channel into seperate vectors
		//multiply by a facto for combining into luma
		vbx_set_vl(1);
		vbx_set_2D(rowlen,sizeof(vbx_word_t),3,3);
		vbx_2D(SVBWU,VMUL,(vbx_uword_t*)v_tmp0,66,line_in+0);
		vbx_2D(SVBWU,VMUL,(vbx_uword_t*)v_tmp1,129,line_in+1);
		vbx_2D(SVBWU,VMUL,(vbx_uword_t*)v_tmp2,25,line_in+2);

		//convert to luma
		vbx_set_vl(rowlen);
		vbx(VVW,VADD,luma_bot,v_tmp0,v_tmp1);
		vbx(VVW,VADD,luma_bot,luma_bot,v_tmp2);
		vbx(SVW,VSHR,luma_bot,8,luma_bot);

		/// Apply [1 2 1] to input luma row
		vbx_set_vl(rowlen-1);
		vbx(VVW,VADD,sobel_bot,luma_bot,luma_bot+1);
		vbx_set_vl(rowlen-2);
		vbx(VVW,VADD,sobel_bot,sobel_bot,sobel_bot+1);

		if (row>1){

			// |grad_y|  = |sobel_top - sobel_bot|;
			vbx(VVW,VABSDIFF,grad_y,sobel_top,sobel_bot);

			//grad_x = | 1 0 -1 |
			//         | 2 0 -2 |  * luma
			//         | 1 - -1 |
			vbx_set_vl(rowlen);
			vbx(VVW,VADD,v_tmp0,luma_top,luma_mid);
			vbx(VVW,VADD,v_tmp1,luma_bot,luma_mid);
			vbx(VVW,VADD,v_tmp0,v_tmp0,v_tmp1);

			vbx_set_vl(rowlen-2);
			vbx(VVW,VABSDIFF,grad_x,v_tmp0,v_tmp0+2);

			//sum gradiaents and threshold at 255
			vbx_word_t* row_out=grad_x;
			vbx(VVW,VADD,row_out,grad_x,grad_y);
			vbx(SVW,VSUB,v_tmp0,255,row_out);
			vbx(SVW,VCMV_LTZ,row_out,255,v_tmp0);

			//copy to other bytes of word
			vbx(SVW,VMUL,row_out,0x010101,row_out);

			//pack into RGB
			vbx_set_vl(3);
			vbx_set_2D(rowlen-2,3,sizeof(vbx_word_t),0);
			vbx_2D(VVB,VMOV,(vbx_byte_t*)row_out,(vbx_byte_t*)row_out,0);
			vbx_byte_t *out=out_vid+((row-1)*pitch + 1)*3;
			vbx_dma_to_host(out,row_out,(rowlen-2)*3);
		}

		//rotate rows
		{
			vbx_word_t* aa;
			aa=luma_top;
			luma_top=luma_mid;
			luma_mid=luma_bot;
			luma_bot=aa;

			aa=sobel_top;
			sobel_top=sobel_mid;
			sobel_mid=sobel_bot;
			sobel_bot=aa;
		}

	}

	//blackout outside pixels
	vbx_set_vl(rowlen*3);
	vbx(SVBU,VMOV,line_in,0,0);

	//top row
	vbx_dma_to_host(out_vid,line_in,rowlen*3);
	//bottom row
	vbx_dma_to_host(out_vid+(rows-1)*rowlen*3,line_in,rowlen*3);
	//left column
	vbx_dma_to_host_2D(out_vid,line_in,3,cols,pitch*3,0);
	//right column
	vbx_dma_to_host_2D(out_vid+(rowlen-1)*3,line_in,3,cols,rowlen*3,0);

	//restore scratchpad allocator state
	vbx_sp_pop();

	//make sure all dma operations are complete before exiting
	vbx_sync();
}