Add CF2 docs and support BIN files in patcher

cf2.md

@@ -0,0 +1,57 @@
+# Binary Bootloader-embedded Config (CF2)
+
+## Motivation
+
+The goal of CF2 is to run the same binary on a number of devices with different
+peripheral configuration, but the same MCU.
+Typically, this has been achieved by embedding identification components in hardware
+(eg. connecting certain MCU pins to GND or 3V) and having the firmware dynamically
+detect these.
+While simple, this only allows a few bits of configuration data to be stored on device.
+
+Instead, we use the bootloader area for storing device specific configuration data.
+Such data is not altered when the device is programmed with new firmware,
+and the said firmware can refer to the configuration data in the bootloader area to
+alter its behavior.
+
+For example, MakeCode Arcade requires a device with 7 buttons (directions, A, B, and MENU),
+a screen from a specific family, and one of the few supported accelerometers.
+The exact configuration depends on the manufacturer, but the binary produced by MakeCode
+will work on any device with the right MCU, provided it has the right configuration
+data in the bootloader area.
+
+Thus, the user only needs to select the type of MCU (which is color coded, 
+and is assigned a simple user-facing name), and the resulting binary will work
+on their device.
+Moreover, they can drag the UF2 file between devices, provided they run the same MCU.
+Once bootloaders are updated with networking support (wired or wireless), one device with 
+a given MCU will be able to flash another.
+
+## Configuration data format
+
+Data comes as pairs of 32 bit unsigned integers (in machine byte order).
+* first pair is `0x1e9e10f1, 0x20227a79`
+* second pair consists of the number of configuration entries, and a zero (reserved)
+* then configuration entries follow, where the first element is the configuration
+  entry key number, and the second is the value (these entries are sorted by key number)
+* finally, a number of zeroes follows (typically at least a few hundred), 
+  to store any additional configuration data in future
+
+The file with definitions of key names can be downloaded from the patcher website (see below).
+
+If you require your own key names, please use 
+[random large key names](https://github.com/Microsoft/uf2#picking-numbers-at-random).
+
+## The Patcher
+
+At https://microsoft.github.io/uf2/patcher/ we provide a tool, which given a UF2 file
+and a configuration definition, binary-patches the UF2 file and lets the user download it.
+The tool also parses existing configuration information from the UF2 file and show it.
+
+Such tool is to be used by maker of devices.
+For example, for MakeCode Arcade, this includes both factories and users who take an existing
+multi-purpose board and connect keys and screen.
+Such user would then download generic MakeCode Arcade bootloader (either a UF2 file,
+which upgrades the bootloader, or a .BIN file with the bootloader) for the given MCU,
+and binary patch it with their configuration.
+Then, they would update the bootloader, and have a Arcade-compatible device.

hf2.md

@@ -14,8 +14,8 @@ ones, but be less efficient.
 In particular, it is suitable for running over USB HID (Human Interface Device),
 which is widely supported in various operating systems without the need for kernel-space
 drivers. It is also possible to run the protocol over a WebUSB link with either a single
-interrupt endpoint or two bulk endpoints, allowing direct access from supported
+interrupt endpoint or two bulk endpoints, as well as using just the control pipe,
-browsers. 
+allowing direct access from supported browsers. 
 
 ## Raw message format
 

patcher/index.html

@@ -43,10 +43,12 @@
     <a href="#" id="apply" class="btn btn-dl">Apply my patch</a>
 
     <h2>Information</h2>
-    <pre><code id="currconfig">Drop UF2 file above to see its config.</code></pre>
+    <pre><code id="currconfig">Drop UF2 or BIN file above to see its config.</code></pre>
 
     <p>
-      <a href="#" onclick="defines()">Download configkeys.h</a>
+      <a href="https://github.com/Microsoft/uf2/blob/master/cf2.md">Learn more</a>
+      or
+      <a href="#" onclick="defines()">download configkeys.h</a>.
     </p>
   </section>
 

patcher/patcher.js

@@ -242,23 +242,43 @@ function readWriteConfig(buf, patch) {
     let cfgLen = 0
     if (patch)
         patch.push(0, 0)
+    let isUF2 = false
+    if (read32(buf, 0) == UF2_MAGIC_START0) {
+        isUF2 = true
+        log("# detected UF2 file")
+    } else {
+        let stackBase = read32(buf, 0)
+        if ((stackBase & 0xff0000ff) == 0x20000000 &&
+            (read32(buf, 4) & 1) == 1) {
+            log("# detected BIN file")
+        } else {
+            err("unknown file format")
+        }
+    }
     for (let off = 0; off < buf.length; off += 512) {
+        let start = 0
+        let payloadLen = 512
+        let addr = off
+
+        if (isUF2) {
+            start = 32
             if (read32(buf, off) != UF2_MAGIC_START0 ||
                 read32(buf, off + 4) != UF2_MAGIC_START1) {
                 err("invalid data at " + off)
             }
+            payloadLen = read32(buf, off + 16)
+            addr = read32(buf, off + 12) - 32
+        }
 
-        const payloadLen = read32(buf, off + 16)
+        for (let i = start; i < start + payloadLen; i += 4) {
-
-        for (let i = 32; i < 32 + payloadLen; i += 4) {
             if (read32(buf, off + i) == CFG_MAGIC0 &&
                 read32(buf, off + i + 4) == CFG_MAGIC1) {
-                let addr = "0x" + (read32(buf, off + 12) + i - 32).toString(16)
+                let addrS = "0x" + (addr + i).toString(16)
                 if (patchPtr === null) {
-                    log(`# Found CFG DATA at ${addr}`)
+                    log(`# Found CFG DATA at ${addrS}`)
                     patchPtr = -4
                 } else {
-                    log(`# Skipping second CFG DATA at ${addr}`)
+                    log(`# Skipping second CFG DATA at ${addrS}`)
                 }
             }
 

patcher/web.js

@@ -54,7 +54,7 @@ function applyPatch() {
         let text = document.getElementById("patch")
         let newcfg = text.value.trim()
         if (!currUF2)
-            log("You have to drop a UF2 file with bootloader above before applying patches.")
+            log("You have to drop a UF2 or BIN file with bootloader above before applying patches.")
         else if (!newcfg)
             log("You didn't give any patch to apply.")
         else {