1 files changed, 154 insertions, 0 deletions
diff --git a/kms++/src/mode_cvt.cpp b/kms++/src/mode_cvt.cpp
new file mode 100644
index 0000000..41503c7
--- /dev/null
+++ b/kms++/src/mode_cvt.cpp
@@ -0,0 +1,154 @@
+// Supports CVT 1.2 reduced blanking modes v1 and v2
+
+#include <kms++/kms++.h>
+#include <cmath>
+
+using namespace std;
+
+namespace kms
+{
+
+static float CELL_GRAN = 8;
+static float CELL_GRAN_RND = round(CELL_GRAN);
+
+struct CVTConsts
+{
+	float CLOCK_STEP;
+	float MIN_V_BPORCH;
+	float RB_H_BLANK;
+	float RB_H_FPORCH;
+	float RB_H_SYNC;
+	float RB_H_BPORCH;
+	float RB_MIN_V_BLANK;
+	float RB_V_FPORCH;
+	float REFRESH_MULTIPLIER;
+};
+
+static const CVTConsts cvt_consts_v1 =
+{
+	.CLOCK_STEP = 0.25,	// Fixed
+	.MIN_V_BPORCH = 6,	// Min
+	.RB_H_BLANK = 160,	// Fixed
+	.RB_H_FPORCH = 48,	// Fixed
+	.RB_H_SYNC = 32,	// Fixed
+	.RB_H_BPORCH = 80,	// Fixed
+	.RB_MIN_V_BLANK = 460,	// Min
+	.RB_V_FPORCH = 3,	// Fixed
+	.REFRESH_MULTIPLIER = 1,// Fixed
+};
+
+static const CVTConsts cvt_consts_v2 =
+{
+	.CLOCK_STEP = 0.001,	// Fixed
+	.MIN_V_BPORCH = 6,	// Fixed
+	.RB_H_BLANK = 80,	// Fixed
+	.RB_H_FPORCH = 8,	// Fixed
+	.RB_H_SYNC = 32,	// Fixed
+	.RB_H_BPORCH = 40,	// Fixed
+	.RB_MIN_V_BLANK = 460,	// Min
+	.RB_V_FPORCH = 1,	// Min
+	.REFRESH_MULTIPLIER = 1,// or 1000/1001
+};
+
+Videomode videomode_from_cvt(uint32_t hact, uint32_t vact, uint32_t refresh, bool ilace, bool reduced_v2, bool video_optimized)
+{
+	CVTConsts c = reduced_v2 ? cvt_consts_v2 : cvt_consts_v1;
+
+	if (video_optimized)
+		c.REFRESH_MULTIPLIER = 1000.0/1001.0;
+
+	bool INT_RQD = ilace;
+
+	float H_PIXELS = hact;
+	float V_LINES = vact;
+	float IP_FREQ_RQD = refresh ? refresh : 60;
+	if (ilace)
+		IP_FREQ_RQD /= 2;
+
+	float V_SYNC_RND;
+
+	if (reduced_v2) {
+		V_SYNC_RND = 8;
+	} else {
+		if (hact * 3 == vact * 4)
+			V_SYNC_RND = 4;
+		else if (hact * 9 == vact * 16)
+			V_SYNC_RND = 5;
+		else if (hact * 10 == vact * 16)
+			V_SYNC_RND = 6;
+		else if (hact == 1280 && (vact == 1024 || vact == 768))
+			V_SYNC_RND = 7;
+		else
+			V_SYNC_RND = 10;
+	}
+
+	// 5.2.1
+	float V_FIELD_RATE_RQD = INT_RQD ? IP_FREQ_RQD * 2 : IP_FREQ_RQD;
+
+	// 5.2.2
+	float H_PIXELS_RND = floor(H_PIXELS / CELL_GRAN_RND) * CELL_GRAN_RND;
+
+	// 5.2.3
+	float LEFT_MARGIN = 0;
+	float RIGHT_MARGIN = 0;
+
+	// 5.2.4
+	float TOTAL_ACTIVE_PIXELS = H_PIXELS_RND + LEFT_MARGIN + RIGHT_MARGIN;
+
+	// 5.2.5
+	float V_LINES_RND = INT_RQD ? floor(V_LINES / 2) : floor(V_LINES);
+
+	// 5.2.6
+	float TOP_MARGIN = 0;
+	float BOT_MARGIN = 0;
+
+	// 5.2.7
+	float INTERLACE = INT_RQD ? 0.5 : 0;
+
+	// 5.4.8
+	float H_PERIOD_EST = ((1000000 / V_FIELD_RATE_RQD) - c.RB_MIN_V_BLANK) / (V_LINES_RND + TOP_MARGIN + BOT_MARGIN);
+
+	// 5.4.9
+	float VBI_LINES = floor(c.RB_MIN_V_BLANK / H_PERIOD_EST) + 1;
+
+	// 5.4.10
+	float RB_MIN_VBI = c.RB_V_FPORCH + V_SYNC_RND + c.MIN_V_BPORCH;
+	float ACT_VBI_LINES = VBI_LINES < RB_MIN_VBI ? RB_MIN_VBI : VBI_LINES;
+
+	// 5.4.11
+	float TOTAL_V_LINES = ACT_VBI_LINES + V_LINES_RND + TOP_MARGIN + BOT_MARGIN + INTERLACE;
+
+	// 5.4.12
+	float TOTAL_PIXELS = c.RB_H_BLANK + TOTAL_ACTIVE_PIXELS;
+
+	// 5.4.13
+	float ACT_PIXEL_FREQ = c.CLOCK_STEP * floor((V_FIELD_RATE_RQD * TOTAL_V_LINES * TOTAL_PIXELS / 1000000 * c.REFRESH_MULTIPLIER) / c.CLOCK_STEP);
+
+	// 5.4.14
+	//float ACT_H_FREQ = 1000 * ACT_PIXEL_FREQ / TOTAL_PIXELS;
+
+	// 5.4.15
+	//float ACT_FIELD_RATE = 1000 * ACT_H_FREQ / TOTAL_V_LINES;
+
+	// 5.4.16
+	//float ACT_FRAME_RATE = INT_RQD ? ACT_FIELD_RATE / 2 : ACT_FIELD_RATE;
+
+	// 3.4.3.7 Adjust vfp
+	if (reduced_v2)
+		c.RB_V_FPORCH = ACT_VBI_LINES - V_SYNC_RND - c.MIN_V_BPORCH;
+
+	Videomode mode;
+
+	mode = videomode_from_timings(ACT_PIXEL_FREQ * 1000,
+				      H_PIXELS_RND, c.RB_H_FPORCH, c.RB_H_SYNC, c.RB_H_BPORCH,
+				      V_LINES_RND * (INT_RQD ? 2 : 1), c.RB_V_FPORCH, V_SYNC_RND, ACT_VBI_LINES - V_SYNC_RND - c.RB_V_FPORCH);
+
+	mode.set_hsync(SyncPolarity::Positive);
+	mode.set_vsync(SyncPolarity::Negative);
+
+	mode.set_interlace(INT_RQD);
+
+	return mode;
+}
+
+}