好久沒有在這里放文章了，今天灌點水，自己寫的小程序。
#define frows 128
#define fcols 128
#define mrows 5
#define mcols 5
float fdem[frows][fcols];
float mdem[mrows][mcols];
#define PRINT_TEST????????\
?printf("\n\n --------mdem array---------");?\
?printf("\n frr=%d, fcc=%d", frr, fcc);??\
?printf("\n mrr=%d, mcc=%d", mrr, mcc);??\
?for(i=mrr; i<mrr+mrows; i++){????\
??int r = i % mrows;??????\
??printf("\n ");???????\
??for(j=mcc; j<mcc+mcols; j++){???\
???int c = j % mcols;?????\
???printf("%0.3f\t ", mdem[r][c]);??\
??}??????????\
?}??????????
int main(int argc, char* argv[])
{
?int i,j;
?int step=0;??//在mem中跳過的格子數
?int steplen=2;?//mem中一個格子對應在file跳過的格子數
?//初始化
?for(i=0; i<frows; i++){
??for(j=0; j<fcols; j++){
???fdem[i][j] = i + j*0.001f;
??}
?}
?int frr=0; int fcc=0; int mrr=0; int mcc=0;
?for(i=mrr; i<mrr+mrows; i++){
??int r = i % mrows;
??for(j=mcc; j<mcc+mcols; j++){
???int c = j % mcols;
???mdem[r][c] = fdem[frr + (i-mrr)*steplen][fcc+ (j-mcc)*steplen];??
??}
?}
?PRINT_TEST;
?//向右平移
?step=3;
?for(j=mcc; j<mcc+step; j++){
??int c = j % mcols;
??for(i=mrr; i<mrr+mrows; i++){
???int r = i % mrows;
???int rr = frr + (i-mrr) * steplen;
???int cc = fcc + (mcols + j-mcc) * steplen;
???mdem[r][c] = fdem[rr][cc];?
??}
?}
?fcc += step * steplen;
?mcc += step;
?PRINT_TEST;
?//向左平移
?step=3;
?for(j=mcc-1; j>=mcc-step; j--){
??int c = (j + mcols) % mcols;
??for(i=mrr; i<mrr+mrows; i++){
???int r = i % mrows;
???int rr = frr + (i-mrr) * steplen;
???int cc = fcc - (mcc-j) * steplen;
???mdem[r][c] = fdem[rr][cc];?
??}
?}
?fcc -= step * steplen;
?mcc -= step;
?PRINT_TEST;
?//向下平移
?step=3;
?for(i=mrr; i<mrr+step; i++){
??int r = i % mrows;
??for(j=mcc; j<mcc+mcols; j++){
???int c = j % mcols;
???int cc = fcc + (j-mcc) * steplen;
???int rr = frr + (mrows + i-mrr) * steplen;
???mdem[r][c] = fdem[rr][cc];?
??}
?}
?frr += step * steplen;
?mrr += step;
?PRINT_TEST;
?
?//向上平移
?step=3;
?for(i=mrr-1; i>=mrr-step; i--){
??int r = (i + mrows) % mrows;
??for(j=mcc; j<mcc+mcols; j++){
???int c = j % mcols;
???int cc = fcc + (j-mcc) * steplen;
???int rr = frr - (mrr-i) * steplen;
???mdem[r][c] = fdem[rr][cc];?
??}
?}
?frr -= step * steplen;
?mrr -= step;
?PRINT_TEST;
?return 0;
}