diff options
| -rw-r--r-- | xrandr.c | 26 |
1 files changed, 22 insertions, 4 deletions
@@ -1323,7 +1323,7 @@ set_gamma(void) output_t *output; for (output = outputs; output; output = output->next) { - int i, size; + int i, size, shift; crtc_t *crtc; XRRCrtcGamma *gamma; float gammaRed; @@ -1347,6 +1347,24 @@ set_gamma(void) continue; } + /* + * The gamma-correction lookup table managed through XRR[GS]etCrtcGamma + * is 2^n in size, where 'n' is the number of significant bits in + * the X Color. Because an X Color is 16 bits, size cannot be larger + * than 2^16. + */ + if (size > 65536) { + fatal("Gamma correction table is impossibly large.\n"); + continue; + } + + /* + * The hardware color lookup table has a number of significant + * bits equal to ffs(size) - 1; shift values so that they + * occupy the MSBs of the 16-bit X Color. + */ + shift = 16 - (ffs(size) - 1); + gamma = XRRAllocGamma(size); if (!gamma) { fatal("Gamma allocation failed.\n"); @@ -1366,21 +1384,21 @@ set_gamma(void) for (i = 0; i < size; i++) { if (gammaRed == 1.0 && output->brightness == 1.0) - gamma->red[i] = (i << 8) + i; + gamma->red[i] = (i << shift); else gamma->red[i] = dmin(pow((double)i/(double)(size - 1), gammaRed) * output->brightness, 1.0) * 65535.0; if (gammaGreen == 1.0 && output->brightness == 1.0) - gamma->green[i] = (i << 8) + i; + gamma->green[i] = (i << shift); else gamma->green[i] = dmin(pow((double)i/(double)(size - 1), gammaGreen) * output->brightness, 1.0) * 65535.0; if (gammaBlue == 1.0 && output->brightness == 1.0) - gamma->blue[i] = (i << 8) + i; + gamma->blue[i] = (i << shift); else gamma->blue[i] = dmin(pow((double)i/(double)(size - 1), gammaBlue) * output->brightness, |