rotate.c

深入理解计算机系统（computer system：a programmer s perpective)是一本非常经典的教材

#include <stdio.h>
#include <stdlib.h>
#include "defs.h"

team_t team = {
    /* Team name */
    "Unused",
    /* First member full name */
    "zangdonghe",
    /* First member email address */
    "0472491",
    /* Second member full name (leave blank if none) */
    "",
    /* Second member email address (blank if none) */
    ""
};


/* The supplied naive version of rotate */
char naive_rotate_descr[] = "Naive Row-wise Traversal of src";
void naive_rotate(int dim, pixel *src, pixel *dst) {
  int i, j;

  for(i=0; i < dim; i++) {
    for(j=0; j < dim; j++) {
      dst[RIDX(dim-1-j,i,dim)] = src[RIDX(i,j,dim)];
    }
  }

  return;
}
char rotate_descr[] = "Currently set to: Naive Row-wise Traversal of src";
void rotate(int dim, pixel *src, pixel *dst) 
{
	int i, j;
	pixel *tsrc,*tsrc2, *t,*hold, *hold2;
	if(dim < 256)
	{
		t = src + dim - 1;
		hold = dst;
		hold2 = dst;
		for (i = 0; i < dim; i+= 2)
		{
			tsrc = t - i;
			tsrc2 = tsrc - 1;
			hold2 += dim;
			*hold = *tsrc;
			*hold2 = *tsrc2;
			hold++;
			hold2++;
			for(j = 1; j < dim; j++)
			{
				tsrc += dim;
				tsrc2 += dim;
				*hold = *tsrc;
				*hold2 = *tsrc2;
				hold++;	
				hold2++;
			}
			hold += dim;
		}
	}
	else
	{
		for (i = 0; i < dim; i+=32)
		{
			for (j = 0; j < dim; j++)
			{
				dst[RIDX(dim-1-i,j,dim)] = src[RIDX(j,i,dim)];
				dst[RIDX(dim-2-i,j,dim)] = src[RIDX(j,i+1,dim)];
				dst[RIDX(dim-3-i,j,dim)] = src[RIDX(j,i+2,dim)];
				dst[RIDX(dim-4-i,j,dim)] = src[RIDX(j,i+3,dim)];
				dst[RIDX(dim-5-i,j,dim)] = src[RIDX(j,i+4,dim)];
				dst[RIDX(dim-6-i,j,dim)] = src[RIDX(j,i+5,dim)];
				dst[RIDX(dim-7-i,j,dim)] = src[RIDX(j,i+6,dim)];
				dst[RIDX(dim-8-i,j,dim)] = src[RIDX(j,i+7,dim)];
				dst[RIDX(dim-9-i,j,dim)] = src[RIDX(j,i+8,dim)];
				dst[RIDX(dim-10-i,j,dim)] = src[RIDX(j,i+9,dim)];
				dst[RIDX(dim-11-i,j,dim)] = src[RIDX(j,i+10,dim)];
				dst[RIDX(dim-12-i,j,dim)] = src[RIDX(j,i+11,dim)];
				dst[RIDX(dim-13-i,j,dim)] = src[RIDX(j,i+12,dim)];
				dst[RIDX(dim-14-i,j,dim)] = src[RIDX(j,i+13,dim)];
				dst[RIDX(dim-15-i,j,dim)] = src[RIDX(j,i+14,dim)];
				dst[RIDX(dim-16-i,j,dim)] = src[RIDX(j,i+15,dim)];
				dst[RIDX(dim-17-i,j,dim)] = src[RIDX(j,i+16,dim)];
				dst[RIDX(dim-18-i,j,dim)] = src[RIDX(j,i+17,dim)];
				dst[RIDX(dim-19-i,j,dim)] = src[RIDX(j,i+18,dim)];
				dst[RIDX(dim-20-i,j,dim)] = src[RIDX(j,i+19,dim)];
				dst[RIDX(dim-21-i,j,dim)] = src[RIDX(j,i+20,dim)];
				dst[RIDX(dim-22-i,j,dim)] = src[RIDX(j,i+21,dim)];
				dst[RIDX(dim-23-i,j,dim)] = src[RIDX(j,i+22,dim)];
				dst[RIDX(dim-24-i,j,dim)] = src[RIDX(j,i+23,dim)];
				dst[RIDX(dim-25-i,j,dim)] = src[RIDX(j,i+24,dim)];
				dst[RIDX(dim-26-i,j,dim)] = src[RIDX(j,i+25,dim)];
				dst[RIDX(dim-27-i,j,dim)] = src[RIDX(j,i+26,dim)];
				dst[RIDX(dim-28-i,j,dim)] = src[RIDX(j,i+27,dim)];
				dst[RIDX(dim-29-i,j,dim)] = src[RIDX(j,i+28,dim)];
				dst[RIDX(dim-30-i,j,dim)] = src[RIDX(j,i+29,dim)];
				dst[RIDX(dim-31-i,j,dim)] = src[RIDX(j,i+30,dim)];
				dst[RIDX(dim-32-i,j,dim)] = src[RIDX(j,i+31,dim)];
			}
		}
	}
}

/* Register different versions for testing */
void register_rotate_functions() {
  add_rotate_function(&rotate, rotate_descr);
  add_rotate_function(&naive_rotate, naive_rotate_descr);
}