| int paramType,␊ |
| VBECRTCInfoBlock * timing )␊ |
| {␊ |
| double h_period_est, h_freq, h_period, h_total_pixels, h_sync_pixels;␊ |
| double h_period, h_total_pixels, h_sync_pixels;␊ |
| double h_active_pixels, h_ideal_duty_cycle, h_blank_pixels, pixel_freq = 0;␊ |
| double v_sync_plus_bp = 0, v_total_lines = 0, v_field_rate_est, v_frame_rate = 0;␊ |
| double v_sync_plus_bp = 0, v_total_lines = 0, v_frame_rate = 0;␊ |
| const double h_pixels = (double) width;␊ |
| const double v_lines = (double) height;␊ |
| ␊ |
|
| double v_field_rate_in = (double) paramValue;␊ |
| ␊ |
| // Estimate the horizontal period␊ |
| h_period_est = ((1 / v_field_rate_in) - kMinVSyncPlusBP / 1000000) /␊ |
| (v_lines + (2 * top_margin_lines) + kMinFrontPorch + interlace) * ␊ |
| 1000000;␊ |
| double h_period_est = ((1 / v_field_rate_in) - kMinVSyncPlusBP / 1000000) /␊ |
| (v_lines + (2 * top_margin_lines) + kMinFrontPorch + interlace) * ␊ |
| 1000000;␊ |
| ␊ |
| // Estimate the vertical field frequency␊ |
| double v_field_rate_est = 1 / h_period_est / v_total_lines * 1000000;␊ |
| ␊ |
| // Number of lines in Vsync + back porch␊ |
| v_sync_plus_bp = Round(kMinVSyncPlusBP / h_period_est);␊ |
| ␊ |
|
| v_total_lines = v_lines + top_margin_lines + bot_margin_lines +␊ |
| v_sync_plus_bp + interlace + kMinFrontPorch;␊ |
| ␊ |
| // Estimate the vertical field frequency␊ |
| v_field_rate_est = 1 / h_period_est / v_total_lines * 1000000;␊ |
| ␊ |
| // Find the actual horizontal period␊ |
| h_period = h_period_est / (v_field_rate_in / v_field_rate_est);␊ |
| ␊ |
|
| if (paramType == kCRTCParamPixelClock)␊ |
| {␊ |
| // Horizontal frequency␊ |
| h_freq = pixel_freq / h_total_pixels * 1000;␊ |
| double h_freq = pixel_freq / h_total_pixels * 1000;␊ |
| ␊ |
| // Number of lines in V sync + back porch␊ |
| v_sync_plus_bp = Round(kMinVSyncPlusBP * h_freq / 1000);␊ |
