Add CVT

2 files changed, 270 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 5e151ea..01632d1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-sources = gtf.c
+sources = gtf.c cvt.c
 objects = $(sources:.c=.o)
 
 all: libminitru.so.0
@@ -10,4 +10,4 @@ clean:
 	gcc -fPIC -c -Wall -o $@ $<
 
 libminitru.so.0: $(sources:.c=.o)
-	gcc -shared -Wl,-soname,$@ -o $@ $< -lm
+	gcc -shared -Wl,-soname,$@ -o $@ $^ -lm
diff --git a/cvt.c b/cvt.c
new file mode 100644
index 0000000..f9472bc
--- /dev/null
+++ b/cvt.c
@@ -0,0 +1,268 @@
+/*
+ * Copyright 2005-2006 Luc Verhaegen.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "minitru-int.h"
+
+/*
+ * Generate a CVT standard mode from HDisplay, VDisplay and VRefresh.
+ *
+ * These calculations are stolen from the CVT calculation spreadsheet written
+ * by Graham Loveridge. He seems to be claiming no copyright and there seems to
+ * be no license attached to this. He apparently just wants to see his name
+ * mentioned.
+ *
+ * This file can be found at http://www.vesa.org/Public/CVT/CVTd6r1.xls
+ *
+ * Comments and structure corresponds to the comments and structure of the xls.
+ * This should ease importing of future changes to the standard (not very
+ * likely though).
+ *
+ * About margins; i'm sure that they are to be the bit between HDisplay and
+ * HBlankStart, HBlankEnd and HTotal, VDisplay and VBlankStart, VBlankEnd and 
+ * VTotal, where the overscan colour is shown. FB seems to call _all_ blanking
+ * outside sync "margin" for some reason. Since we prefer seeing proper
+ * blanking instead of the overscan colour, and since the Crtc* values will
+ * probably get altered after us, we will disable margins altogether. With
+ * these calculations, Margins will plainly expand H/VDisplay, and we don't
+ * want that. -- libv
+ *
+ */
+struct mt_mode *
+mt_ct_mode(int hdisplay, int vdisplay, float vrefresh, uint32_t flags)
+{
+    struct mt_mode *mode = calloc(1, sizeof(struct mt_mode));
+    int interlaced = !!(flags & MT_FLAG_INTERLACED);
+    int reduced = !!(flags & MT_FLAG_REDUCED);
+
+    /* 1) top/bottom margin size (% of height) - default: 1.8 */
+#define CVT_MARGIN_PERCENTAGE 1.8    
+
+    /* 2) character cell horizontal granularity (pixels) - default 8 */
+#define CVT_H_GRANULARITY 8
+
+    /* 4) Minimum vertical porch (lines) - default 3 */
+#define CVT_MIN_V_PORCH 3
+
+    /* 4) Minimum number of vertical back porch lines - default 6 */
+#define CVT_MIN_V_BPORCH 6
+
+    /* Pixel Clock step (kHz) */
+#define CVT_CLOCK_STEP 250
+
+    uint32_t margins = 0;
+    float  vfieldrate, hperiod;
+    int  hdisplayrnd, hmargin;
+    int  vdisplayrnd, vmargin, vsync;
+    float  interlace; /* please rename this */
+
+    /* CVT default is 60.0Hz */
+    if (!vrefresh)
+        vrefresh = 60.0;
+
+    /* 1. Required field rate */
+    if (interlaced)
+        vfieldrate = vrefresh * 2;
+    else
+        vfieldrate = vrefresh;
+
+    /* 2. Horizontal pixels */
+    hdisplayrnd = hdisplay - (hdisplay % CVT_H_GRANULARITY);
+
+    /* 3. Determine left and right borders */
+    if (margins) {
+        /* right margin is actually exactly the same as left */
+        hmargin = (((float) hdisplayrnd) * CVT_MARGIN_PERCENTAGE / 100.0);
+        hmargin -= hmargin % CVT_H_GRANULARITY;
+    } else
+        hmargin = 0;
+
+    /* 4. Find total active pixels */
+    mode->hdisplay = hdisplayrnd + 2*hmargin;
+
+    /* 5. Find number of lines per field */
+    if (interlaced)
+        vdisplayrnd = vdisplay / 2;
+    else
+        vdisplayrnd = vdisplay;
+
+    /* 6. Find top and bottom margins */
+    /* nope. */
+    if (margins)
+        /* top and bottom margins are equal again. */
+        vmargin = (((float) vdisplayrnd) * CVT_MARGIN_PERCENTAGE / 100.0);
+    else
+        vmargin = 0;
+
+    mode->vdisplay = vdisplay + 2*vmargin;
+
+    /* 7. Interlace */
+    if (interlaced)
+        interlace = 0.5;
+    else
+        interlace = 0.0;
+
+    /* Determine VSync Width from aspect ratio */
+    if (!(vdisplay % 3) && ((vdisplay * 4 / 3) == hdisplay))
+        vsync = 4;
+    else if (!(vdisplay % 9) && ((vdisplay * 16 / 9) == hdisplay))
+        vsync = 5;
+    else if (!(vdisplay % 10) && ((vdisplay * 16 / 10) == hdisplay))
+        vsync = 6;
+    else if (!(vdisplay % 4) && ((vdisplay * 5 / 4) == hdisplay))
+        vsync = 7;
+    else if (!(vdisplay % 9) && ((vdisplay * 15 / 9) == hdisplay))
+        vsync = 7;
+    else /* Custom */
+        vsync = 10;
+
+    if (!reduced) { /* simplified GTF calculation */
+
+        /* 4) Minimum time of vertical sync + back porch interval (µs) 
+         * default 550.0 */
+#define CVT_MIN_VSYNC_BP 550.0
+
+        /* 3) Nominal HSync width (% of line period) - default 8 */
+#define CVT_HSYNC_PERCENTAGE 8
+
+        float  hblankpercentage;
+        int  vsyncandbackporch, vbackporch;
+        int  hblank;
+
+        /* 8. Estimated Horizontal period */
+        hperiod = ((float) (1000000.0 / vfieldrate - CVT_MIN_VSYNC_BP)) / 
+            (vdisplayrnd + 2 * vmargin + CVT_MIN_V_PORCH + interlace);
+
+        /* 9. Find number of lines in sync + backporch */
+        if (((int)(CVT_MIN_VSYNC_BP / hperiod) + 1) < (vsync + CVT_MIN_V_PORCH))
+            vsyncandbackporch = vsync + CVT_MIN_V_PORCH;
+        else
+            vsyncandbackporch = (int)(CVT_MIN_VSYNC_BP / hperiod) + 1;
+
+        /* 10. Find number of lines in back porch */
+        vbackporch = vsyncandbackporch - vsync;
+
+        /* 11. Find total number of lines in vertical field */
+        mode->vtotal = vdisplayrnd + 2 * vmargin + vsyncandbackporch + interlace
+            + CVT_MIN_V_PORCH;
+
+        /* 5) Definition of Horizontal blanking time limitation */
+        /* Gradient (%/kHz) - default 600 */
+#define CVT_M_FACTOR 600
+
+        /* Offset (%) - default 40 */
+#define CVT_C_FACTOR 40
+
+        /* Blanking time scaling factor - default 128 */
+#define CVT_K_FACTOR 128
+
+        /* Scaling factor weighting - default 20 */
+#define CVT_J_FACTOR 20
+
+#define CVT_M_PRIME CVT_M_FACTOR * CVT_K_FACTOR / 256
+#define CVT_C_PRIME (CVT_C_FACTOR - CVT_J_FACTOR) * CVT_K_FACTOR / 256 + \
+        CVT_J_FACTOR
+
+        /* 12. Find ideal blanking duty cycle from formula */
+        hblankpercentage = CVT_C_PRIME - CVT_M_PRIME * hperiod/1000.0;
+
+        /* 13. Blanking time */
+        if (hblankpercentage < 20)
+            hblankpercentage = 20;
+
+        hblank = mode->hdisplay * hblankpercentage/(100.0 - hblankpercentage);
+        hblank -= hblank % (2*CVT_H_GRANULARITY);
+        
+        /* 14. Find total number of pixels in a line. */
+        mode->htotal = mode->hdisplay + hblank;
+
+        /* Fill in HSync values */
+        mode->hsyncend = mode->hdisplay + hblank / 2;
+
+        mode->hsyncstart = mode->hsyncend - 
+            (mode->htotal * CVT_HSYNC_PERCENTAGE) / 100;
+        mode->hsyncstart += CVT_H_GRANULARITY - 
+            mode->hsyncstart % CVT_H_GRANULARITY;
+
+        /* Fill in VSync values */
+        mode->vsyncstart = mode->vdisplay + CVT_MIN_V_PORCH;
+        mode->vsyncend = mode->vsyncstart + vsync;
+
+    } else { /* Reduced blanking */
+        /* Minimum vertical blanking interval time (µs) - default 460 */
+#define CVT_RB_MIN_VBLANK 460.0
+
+        /* Fixed number of clocks for horizontal sync */
+#define CVT_RB_H_SYNC 32.0
+
+        /* Fixed number of clocks for horizontal blanking */
+#define CVT_RB_H_BLANK 160.0
+
+        /* Fixed number of lines for vertical front porch - default 3 */
+#define CVT_RB_VFPORCH 3
+
+        int  vbilines;
+
+        /* 8. Estimate Horizontal period. */
+        hperiod = ((float) (1000000.0 / vfieldrate - CVT_RB_MIN_VBLANK)) / 
+            (vdisplayrnd + 2*vmargin);
+
+        /* 9. Find number of lines in vertical blanking */
+        vbilines = ((float) CVT_RB_MIN_VBLANK) / hperiod + 1;
+
+        /* 10. Check if vertical blanking is sufficient */
+        if (vbilines < (CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH))
+            vbilines = CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH;
+        
+        /* 11. Find total number of lines in vertical field */
+        mode->vtotal = vdisplayrnd + 2 * vmargin + interlace + vbilines;
+
+        /* 12. Find total number of pixels in a line */
+        mode->htotal = mode->hdisplay + CVT_RB_H_BLANK;
+
+        /* Fill in HSync values */
+        mode->hsyncend = mode->hdisplay + CVT_RB_H_BLANK / 2;
+        mode->hsyncstart = mode->hsyncend - CVT_RB_H_SYNC;
+
+        /* Fill in VSync values */
+        mode->vsyncstart = mode->vdisplay + CVT_RB_VFPORCH;
+        mode->vsyncend = mode->vsyncstart + vsync;
+    }
+
+    /* 15/13. Find pixel clock frequency (kHz for xf86) */
+    mode->clock = mode->htotal * 1000.0 / hperiod;
+    mode->clock -= mode->clock % CVT_CLOCK_STEP;
+
+    /* 18/16. Find actual vertical frame frequency */
+    /* ignore - just set the mode flag for interlaced */
+    if (interlaced)
+        mode->vtotal *= 2;
+
+    if (reduced)
+        mode->flags |= MT_FLAG_PHSYNC | MT_FLAG_NVSYNC;
+    else
+        mode->flags |= MT_FLAG_NHSYNC | MT_FLAG_PVSYNC;
+
+    if (interlaced)
+        mode->flags |= MT_FLAG_INTERLACED;
+
+    return mode;
+}