From dab839ab662d57963151159656eca25c0a927050 Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@openmoko.org>
Date: Sun, 24 Apr 2011 20:01:12 -0300
Subject: [PATCH] ubb-vga.c: moved line length and timing to variables

- ubb-vga.c (line_pairs, line, frame, tricolor, grid, session): line
  length is now kept in a variable, instead of hard-coding its value
  and the values derived from it
- ubb-vga.c (line_cycles, line, hdelay): the total line duration is now
  kept in a variable, instead of hard-coding it all over the place
---
 ubb-vga/ubb-vga.c | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/ubb-vga/ubb-vga.c b/ubb-vga/ubb-vga.c
index 03b66dc..4abd66e 100644
--- a/ubb-vga/ubb-vga.c
+++ b/ubb-vga/ubb-vga.c
@@ -203,7 +203,7 @@ static void cleanup(void)
 /* ----- Prefetch and delay logic ------------------------------------------ */
 
 
-#define	BURST		32
+#define	BURST		32	/* bytes */
 
 
 static inline void prefetch(const uint8_t *prefetch, int words)
@@ -229,6 +229,10 @@ static void until(uint16_t cycles)
 /* ----- Frame buffer output ----------------------------------------------- */
 
 
+static int line_pairs = 160;	/* set/unset pairs */
+static int line_cycles = US(36); /* nominally 31.77 us, but we're too slow  */
+
+
 void setup(void)
 {
 	mlockall(MCL_CURRENT | MCL_FUTURE);
@@ -244,21 +248,20 @@ static void line(const uint8_t *line, const uint8_t *fetch)
 	/* HSYNC */
 	*tcnt = 0;
 	*pddatc = HSYNC;
-	prefetch(fetch, 160);
+	prefetch(fetch, line_pairs);
 	until(US(3.77));
 	*pddats = HSYNC;
 
 	/* Front porch */
 	until(US(3.77+1.79));
 
-	while (p != line+320) {
+	while (p != line+2*line_pairs) {
 		*pddats = *p++ << 8;
 		*pddatc = *p++ << 8;
 	}
 
 	/* Back porch */
-	until(US(31.77));
-	until(US(36));
+	until(line_cycles);
 }
 
 
@@ -269,8 +272,7 @@ static void hdelay(int cycles)
 		*pddatc = HSYNC;
 		until(US(3.77));
 		*pddats = HSYNC;
-		until(US(31.77));
-		until(US(36));
+		until(line_cycles);
 	}
 }
 
@@ -290,14 +292,13 @@ static void frame(const uint8_t *f)
 	until(US(3.77));
 	*pddats = HSYNC;
 
-	prefetch(f, 160);
-	until(US(31.77));
-	until(US(36));
+	prefetch(f, line_pairs);
+	until(line_cycles);
 	hdelay(31);
 
-	for (p = f; p != f+240*320; p += 320) {
-		line(p, p+160);
-		line(p, p+320);
+	for (p = f; p != f+240*2*line_pairs; p += 2*line_pairs) {
+		line(p, p+line_pairs);
+		line(p, p+2*line_pairs);
 	}
 
 	/* Back porch */
@@ -322,18 +323,19 @@ static uint32_t pattern(int set, int r, int g, int b)
 
 static void tricolor(uint32_t *f)
 {
+	int pairs = 2*line_pairs*240;
 	int i;
 
-	for (i = 0; i != 320*240/3; i++) {
+	for (i = 0; i != pairs/3; i++) {
 		f[i & ~1] = R;
 		f[i | 1] = G | B;
 	}
-	for (; i != 320*240*2/3; i++) {
+	for (; i != pairs*2/3; i++) {
 		f[i & ~1] = G;
 		f[i | 1] = R | B;
 	}
 
-	for (; i != 320*240; i++) {
+	for (; i != pairs; i++) {
 		f[i & ~1] = B;
 		f[i | 1] = R | G;
 	}
@@ -355,9 +357,10 @@ static void grid(uint8_t *f)
 	int i, x, y;
 
 	for (i = 0; i != 8; i++) {
-		x = i*40+20;
+		x = i*line_pairs/4+line_pairs/8;
 		for (y = 0; y != 240; y++) {
-			f[y*320+x] = f[y*320+x+1] = col[i] >> 8;
+			uint8_t *p = f+y*2*line_pairs+x;
+			p[0] = p[1] = col[i] >> 8;
 		}
 	}
 }
@@ -385,7 +388,7 @@ static void grab(uint8_t *f)
 
 static void session(int frames)
 {
-	uint8_t f[320*(240+1)];
+	uint8_t f[2*line_pairs*(240+1)];
 	int i;
 
 	memset(f, 0, sizeof(f));