Merge refactor into i2c-wip:

Squashed commit of the following:

commit 4d6662dadfda7f2fd55107535165dc98a0638a3c
Merge: 174d9ab 7ddc844
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Fri Mar 4 23:18:29 2011 -0500

    Merge remote branch 'origin/refactor' into refactor

commit 174d9ab73cc3387a3812e6f3d3e97519bf5b2150
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Fri Mar 4 23:16:53 2011 -0500

    USBSerial docs fix.

commit f217acb73d94f0a88bf33a42684e6e988dcb3685
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Fri Mar 4 20:25:26 2011 -0500

    Brought examples/ up to date; PIN_MAP bugfix for D24.

commit c4ba3ba05fc39ef260cd80d91759966952df74ae
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Fri Mar 4 19:16:42 2011 -0500

    Cosmetic/documentation changes to adc.c

commit e7747b4eb831621951deef6d31629f55cb5c3500
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Fri Mar 4 19:16:07 2011 -0500

    Cosmetic changes to wirish/main.cxx

commit e2f9d4116e59d8487c936989384228ea084a3501
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Fri Mar 4 19:15:24 2011 -0500

    Untabifying docs/source/conf.py

commit 7ddc84481b4eebe337065a0219e3d8dc000791e5
Author: Perry Hung <iperry@gmail.com>
Date:   Wed Mar 2 00:30:19 2011 -0500

    cscope: Find .S instead of .s files

commit 62cb09ed6357eae58b0234fbc074c44e9c0aa5e5
Author: Marti Bolivar <mbolivar@leaflabs.com>
Date:   Wed Mar 2 00:07:10 2011 -0500

    Fixing typo in main.cpp.example.

1 files changed, 103 insertions, 59 deletions

diff --git a/examples/vga-leaf.cpp b/examples/vga-leaf.cpp
index d1c6d7d..9d9fce2 100644
--- a/examples/vga-leaf.cpp
+++ b/examples/vga-leaf.cpp
@@ -1,21 +1,21 @@
 /*
- Crude VGA Output
+ VGA Output
 
- Outputs a red and white leaf to VGA. This implementation is crude and noisy,
- but a fun demo. It should run most VGA monitors at 640x480, though it does
- not follow the timing spec very carefully. Real twisted or shielded wires,
- proper grounding, and not doing this on a breadboard are recommended (but
- it seems to work ok without).
+ Outputs a red and white leaf to VGA.  It should run most VGA monitors
+ at 640x480, though it does not follow the timing spec very
+ carefully. Real twisted or shielded wires, proper grounding, and not
+ doing this on a breadboard are recommended (but it seems to work ok
+ without).
 
- SerialUSB is disabled to get rid of most interrupts (which mess with timing);
- the SysTick is probably the source of the remaining flickers. This means that
- you have to use perpetual bootloader or the reset button to flash new 
- programs.
+ SerialUSB and SysTick are disabled to get rid of the most frequently
+ occurring interrupts (which mess with timing). This means that you
+ have to use perpetual bootloader mode or the reset button to flash
+ new programs.
 
  How to wire this to a VGA port:
-    D5 via ~200ohms to VGA Red     (1)
-    D6 via ~200ohms to VGA Green   (2)
-    D7 via ~200ohms to VGA Blue    (3)
+    D6 via ~200ohms to VGA Red     (1)
+    D7 via ~200ohms to VGA Green   (2)
+    D8 via ~200ohms to VGA Blue    (3)
     D11 to VGA VSync               (14)  (swapped?)
     D12 to VGA HSync               (13)  (swapped?)
     GND to VGA Ground              (5)
@@ -24,48 +24,71 @@
  See also:
   - http://pinouts.ru/Video/VGA15_pinout.shtml
   - http://www.epanorama.net/documents/pc/vga_timing.html
- 
+
  Created 20 July 2010
  By Bryan Newbold for LeafLabs
  This code is released with no strings attached.
- 
+
+ Modified 4 March 2011
+ By Marti Bolivar
+ Disabled SysTick, kept up-to-date with libmaple.
  */
 
+// FIXME: generalize for Native and Mini
+
 #include "wirish.h"
 
-#define LED_PIN 13
+#define LED_PIN BOARD_LED_PIN
 
-// Pinouts
-#define VGA_R 5     // STM32: B6
-#define VGA_G 6     // STM32: A8
-#define VGA_B 7     // STM32: A9
+// Pinouts -- you also must change the GPIO macros below if you change
+// these
+#define VGA_R 6     // STM32: A8
+#define VGA_G 7     // STM32: A9
+#define VGA_B 8     // STM32: A10
 #define VGA_V 11    // STM32: A6
 #define VGA_H 12    // STM32: A7
 
-// These low level macros make GPIO writes much faster
-#define VGA_R_HIGH (GPIOB_BASE)->BSRR = BIT(6)
-#define VGA_R_LOW  (GPIOB_BASE)->BRR  = BIT(6)
-#define VGA_G_HIGH (GPIOA_BASE)->BSRR = BIT(8)
-#define VGA_G_LOW  (GPIOA_BASE)->BRR  = BIT(8)
-#define VGA_B_HIGH (GPIOA_BASE)->BSRR = BIT(9)
-#define VGA_B_LOW  (GPIOA_BASE)->BRR  = BIT(9)
-#define VGA_V_HIGH (GPIOA_BASE)->BSRR = BIT(6)
-#define VGA_V_LOW  (GPIOA_BASE)->BRR  = BIT(6)
-#define VGA_H_HIGH (GPIOA_BASE)->BSRR = BIT(7)
-#define VGA_H_LOW  (GPIOA_BASE)->BRR  = BIT(7)
+// These low level (and STM32 specific) macros make GPIO writes much
+// faster
+#define ABSRR ((volatile uint32*)0x40010810)
+#define ABRR  ((volatile uint32*)0x40010814)
+
+#define RBIT 8                  // (see pinouts)
+#define GBIT 9
+#define BBIT 10
+
+#define VGA_R_HIGH *ABSRR = BIT(RBIT)
+#define VGA_R_LOW  *ABRR  = BIT(RBIT)
+#define VGA_G_HIGH *ABSRR = BIT(GBIT)
+#define VGA_G_LOW  *ABRR  = BIT(GBIT)
+#define VGA_B_HIGH *ABSRR = BIT(BBIT)
+#define VGA_B_LOW  *ABRR  = BIT(BBIT)
+
+#define ON_COLOR   BIT(RBIT)
+#define OFF_COLOR  (BIT(RBIT) | BIT(GBIT) | BIT(BBIT))
+
+// set has priority, so clear every bit and set some given bits:
+#define VGA_COLOR(c) (*ABSRR = c |                                      \
+                      BIT(RBIT+16) | BIT(GBIT+16) | BIT(BBIT+16))
+
+#define VGA_V_HIGH *ABSRR = BIT(6)
+#define VGA_V_LOW  *ABRR  = BIT(6)
+#define VGA_H_HIGH *ABSRR = BIT(7)
+#define VGA_H_LOW  *ABRR  = BIT(7)
 
 void isr_porch(void);
 void isr_start(void);
 void isr_stop(void);
 void isr_update(void);
 
-uint8 toggle;
 uint16 x = 0;       // X coordinate
 uint16 y = 0;       // Y coordinate
-uint8 v_active = 1; // Are we in the image?
+uint16 logo_y = 0;  // Y coordinate, mapped into valid logo index (for speed)
+bool v_active = true; // Are we in the image?
 
-// 1-bit!
-uint8 logo[18][16] = {
+const uint8 x_max = 16;
+const uint8 y_max = 18;
+uint32 logo[y_max][x_max] = {
     {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,},
     {0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,},
     {0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,},
@@ -99,9 +122,20 @@ void setup() {
     digitalWrite(VGA_H, HIGH);
     digitalWrite(VGA_V, HIGH);
 
+    // Fill the logo array with color patterns corresponding to its
+    // truth value.  Note that we could get more tricky here, since
+    // there are 3 bits of color.
+    for (int y = 0; y < y_max; y++) {
+        for (int x = 0; x < x_max; x++) {
+            logo[y][x] = logo[y][x] ? ON_COLOR : OFF_COLOR;
+        }
+    }
+
     // This gets rid of the majority of the interrupt artifacts;
+    // there's still a glitch for low values of y, but let's not worry
+    // about that. (Probably due to the hackish way vsync is done).
     SerialUSB.end();
-    SystemTick.end();
+    systick_disable();
 
     // Configure
     Timer4.pause(); // while we configure
@@ -120,14 +154,13 @@ void setup() {
     Timer4.attachCompare3Interrupt(isr_stop);
     Timer4.setCompare4(1);      // Could be zero I guess
     Timer4.attachCompare4Interrupt(isr_update);
-    
+
     Timer4.setCount(0);         // Ready...
     Timer4.resume();            // Go!
 }
 
 void loop() {
-    toggle ^= 1;
-    digitalWrite(LED_PIN, toggle);
+    toggleLED();
     delay(100);
 
     // Everything happens in the interrupts!
@@ -139,51 +172,59 @@ void loop() {
 void isr_porch(void) {
     VGA_H_HIGH;
     y++;
+    logo_y = map(y, 0, 478, 0, y_max);
     // Back to the top
-    if(y>=523) {
-        y=1;
-        v_active = 1;
+    if(y >= 523) {
+        y = 1;
+        logo_y = 0;
+        v_active = true;
         return;
     }
     // Other vsync stuff below the image
-    if(y>=492) {
+    if(y >= 492) {
         VGA_V_HIGH;
         return;
     }
-    if(y>=490) {
+    if(y >= 490) {
         VGA_V_LOW;
         return;
     }
-    if(y>=479) { 
-        v_active = 0;
+    if(y >= 479) {
+        v_active = false;
         return;
     }
 }
 
 // This is the main horizontal sweep
-void isr_start(void) {  
+void isr_start(void) {
     // Skip if we're not in the image at all
-    if(!v_active) { return; }
+    if (!v_active) {
+        return;
+    }
 
     // Start Red
     VGA_R_LOW;
     VGA_R_HIGH;
 
-    // For each "pixel" (really 20 or so screen pixels?) go red or white
-    for(x=0; x<32; x++) {
-        if(logo[y/28][x/2]) {
-            VGA_G_HIGH;
-            VGA_B_HIGH;
-        } else {
-            VGA_G_LOW;
-            VGA_B_LOW;
-        }
+    // For each "pixel", go ON_COLOR or OFF_COLOR
+    for(x = 0; x < 16; x++) {
+        // setting the color several times is just an easy way to
+        // delay, so the image is wider.  if you only do the following
+        // once, you'll be able to make the logo array a lot wider:
+        VGA_COLOR(logo[logo_y][x]);
+        VGA_COLOR(logo[logo_y][x]);
+        VGA_COLOR(logo[logo_y][x]);
+        VGA_COLOR(logo[logo_y][x]);
+        VGA_COLOR(logo[logo_y][x]);
+        VGA_COLOR(logo[logo_y][x]);
     }
 }
 
 // End of the horizontal line
 void isr_stop(void) {
-    if(!v_active) { return; }
+    if (!v_active) {
+        return;
+    }
     VGA_R_LOW;
     VGA_G_LOW;
     VGA_B_LOW;
@@ -194,8 +235,11 @@ void isr_update(void) {
     VGA_H_LOW;
 }
 
-int main(void) {
+__attribute__((constructor)) void premain() {
     init();
+}
+
+int main(void) {
     setup();
 
     while (1) {