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Clean up a little, do XOR w/32-bit ops

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This commit is contained in:
Phillip Burgess 2017-11-09 23:07:31 -08:00
parent 9c4b801637
commit 3a136f2d98
1 changed files with 31 additions and 26 deletions
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57
main.c
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@ -64,6 +64,7 @@ int process() {
return -1;
}
// Allocate 3 screen buffers (current, prior, delta)
screenbuf[0] = (uint16_t *)malloc(vinfo.xres * vinfo.yres * 2 * 3);
if(!screenbuf[0]) {
printf("malloc fail");
@ -89,37 +90,41 @@ int process() {
// Transfer snamshot to screenbuf
vc_dispmanx_resource_read_data(screen_resource, &rect1,
(char *)screenbuf[bufNum], vinfo.xres * vinfo.bits_per_pixel / 8);
// Calculate delta between two screenbufs
for(int i=0; i<vinfo.xres * vinfo.yres; i++) {
screenbuf[2][i] = screenbuf[0][i] ^ screenbuf[1][i];
// Calculate XOR between two screenbufs
uint32_t *p0 = (uint32_t *)screenbuf[0], // 32-bit ops
*p1 = (uint32_t *)screenbuf[1],
*p2 = (uint32_t *)screenbuf[2];
for(int i=0; i<vinfo.xres * vinfo.yres / 2; i++) {
p2[i] = p0[i] ^ p1[i];
}
// Find bounding rect of nonzero pixels
uint32_t first, last;
// Find first nonzero word
for(first=0; (first < (vinfo.xres * vinfo.yres)) &&
!screenbuf[2][first]; first++);
// Find first nonzero lword
for(first=0; (first < (vinfo.xres * vinfo.yres / 2)) && !p2[first];
first++);
if(first < (vinfo.xres * vinfo.yres)) {
// Find last nonzero word
for(last=vinfo.xres * vinfo.yres - 1; (last > first) &&
!screenbuf[2][last]; last--);
if(first < (vinfo.xres * vinfo.yres / 2)) { // ANY change?
// Find last nonzero lword
for(last=(vinfo.xres * vinfo.yres / 2) - 1; (last > first) &&
!p2[last]; last--);
int firstRow = first / vinfo.xres;
int lastRow = last / vinfo.xres;
// printf("%d %d\n", firstRow, lastRow);
int firstRow = first / (vinfo.xres / 2);
int lastRow = last / (vinfo.xres / 2);
#if 0
// Try a full-width copy (single operation)
memcpy(
(uint16_t *)&fbp[(firstRow * vinfo.xres) * 2],
&screenbuf[bufNum][firstRow * vinfo.xres],
vinfo.xres * (lastRow - firstRow + 1) * 2);
// Let's try a full-width copy (single memcpy operation)
memcpy(
(uint16_t *)&fbp[firstRow * vinfo.xres * 2],
&screenbuf[bufNum][firstRow * vinfo.xres],
vinfo.xres * (lastRow - firstRow + 1) * 2);
#else
// Try rect bounds (multiple memcpy's)
// Find actual rect bounds and use memcpy-per-row
int firstCol = vinfo.xres - 1, lastCol = 0;
for(int row=firstRow; row <= lastRow; row++) {
uint16_t *s = &screenbuf[2][row * vinfo.xres];
uint16_t *s = (uint16_t *)&p2[row * vinfo.xres / 2];
for(int col=0; col<vinfo.xres; col++) {
if(s[col]) {
if(col < firstCol) firstCol = col;
@ -129,12 +134,12 @@ memcpy(
}
// printf("(%d,%d) (%d,%d)\n", firstCol, firstRow, lastCol, lastRow);
int width = lastCol - firstCol + 1;
uint16_t *src, *dst;
src = &screenbuf[bufNum][firstRow * vinfo.xres + firstCol];
dst = (uint16_t *)&fbp[(firstRow * vinfo.xres + firstCol) * 2];
int bytes = (lastCol - firstCol + 1) * 2;
uint16_t
*src = &screenbuf[bufNum][firstRow * vinfo.xres + firstCol],
*dst = (uint16_t *)&fbp[(firstRow * vinfo.xres + firstCol) * 2];
for(int row=firstRow; row <= lastRow; row++) {
memcpy(dst, src, width * 2);
memcpy(dst, src, bytes);
src += vinfo.xres;
dst += vinfo.xres;
}
@ -142,7 +147,7 @@ memcpy(
#endif
bufNum = 1 - bufNum;
}
usleep(1000000 / 30);
usleep(1000000 / 30); // 30 fps max
}
munmap(fbp, finfo.smem_len);