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ubb-vga: gently prepare the code for sharing mode information
This is tricky: if we just make "mode" global, the whole timing may fall apart, with the DMA locking up. So let's take small bisectable steps to get there ... - ubb-vga.c (struct mode), ubb-vga.h: moved mode entry declaration to ubb-vga.h - ubb-vga.c (mode_db): moved up
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@ -45,6 +45,47 @@ static volatile void *base;
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static int bad;
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#define US(us) ((uint16_t) ((us)*112))
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static const struct mode mode_db[] = {
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{ "640x480", 640, 480, 11, US(29.7), US(0.79+3.77-0.3) },
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{ "800x600", 800, 600, 8, US(28.7), US(2.0+3.3+0.3) },
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/* the next one may work after adjusting the timing in "frame" */
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{ "800x600", 800, 600, 8, US(28.2), US(2.0+3.3+0.3-0.3) },
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/* the 1024x768 below is not great but has good parameter tolerance */
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{ "1024x768", 1024, 768, 8, US(36.0), US(2.0+3.3) },
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/* illustrate underruns */
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{ "1024x768ur", 1024, 768, 7, US(33.5), US(0.4+2.1+0.5) },
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{ NULL }
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};
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/*
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* Adjustment value tests with the XEN-1510 (640x480):
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*
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* Adjustment Tries Good Jam FIFO jitter
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* Quick load
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* -0.0 10 3 7 0 n
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* -0.1 10 5 5 0 n
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* -0.2 10 6 4 0 n
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* -0.3 10 7 3 0 n
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* 10 5 5 0 y
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* -0.4 10 1 0 9 n
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* 10 5 0 5 n repeat
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* 10 5 0 5 y
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* -0.5 10 3 0 7 n
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* 10 7 0 3 y
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* -1.0 5 0 5 0
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*
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* Good = image is stable
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* Jam = does not detect the signal properly, loss of HSYNC, artefacts,
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* or no image at all
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* FIFO jitter = some lines get shifted by a "digital" amount
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*/
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static const struct mode *mode = mode_db;
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/* ----- I/O pin assignment ------------------------------------------------ */
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@ -172,9 +213,6 @@ static void cleanup(void)
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/* ----- Delay logic ------------------------------------------------------- */
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#define US(us) ((uint16_t) ((us)*112))
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static void until(uint16_t cycles)
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{
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while ((TCNT(TIMER) & 0xffff) < cycles);
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@ -184,48 +222,6 @@ static void until(uint16_t cycles)
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/* ----- Frame buffer output ----------------------------------------------- */
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static const struct mode {
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const char *name;
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int xres, yres;
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int clkdiv; /* pixel clock = 336 MHz/(clkdiv+1) */
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int line_cycles; /* 31.77 us for official VGA */
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int hsync_end; /* 0.79+3.77 us for official VGA */
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} mode_db[] = {
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{ "640x480", 640, 480, 11, US(29.7), US(0.79+3.77-0.3) },
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{ "800x600", 800, 600, 8, US(28.7), US(2.0+3.3+0.3) },
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/* the next one may work after adjusting the timing in "frame" */
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{ "800x600", 800, 600, 8, US(28.2), US(2.0+3.3+0.3-0.3) },
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/* the 1024x768 below is not great but has good parameter tolerance */
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{ "1024x768", 1024, 768, 8, US(36.0), US(2.0+3.3) },
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/* illustrate underruns */
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{ "1024x768ur", 1024, 768, 7, US(33.5), US(0.4+2.1+0.5) },
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{ NULL }
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}, *mode = mode_db;
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/*
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* Adjustment value tests with the XEN-1510 (640x480):
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*
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* Adjustment Tries Good Jam FIFO jitter
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* Quick load
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* -0.0 10 3 7 0 n
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* -0.1 10 5 5 0 n
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* -0.2 10 6 4 0 n
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* -0.3 10 7 3 0 n
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* 10 5 5 0 y
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* -0.4 10 1 0 9 n
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* 10 5 0 5 n repeat
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* 10 5 0 5 y
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* -0.5 10 3 0 7 n
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* 10 7 0 3 y
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* -1.0 5 0 5 0
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*
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* Good = image is stable
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* Jam = does not detect the signal properly, loss of HSYNC, artefacts,
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* or no image at all
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* FIFO jitter = some lines get shifted by a "digital" amount
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*/
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static void setup(void)
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{
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mlockall(MCL_CURRENT | MCL_FUTURE);
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@ -23,6 +23,15 @@
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#define Y_VAL (1 << 2)
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struct mode {
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const char *name; /* NULL for end of table */
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int xres, yres;
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int clkdiv; /* pixel clock = 336 MHz/(clkdiv+1) */
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int line_cycles; /* 31.77 us for official VGA */
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int hsync_end; /* 0.79+3.77 us for official VGA */
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};
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void *map(off_t addr, size_t size);
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