From 4dfad70e9b966563157732323d2a44319b77520a Mon Sep 17 00:00:00 2001
From: Andrew Lalis <andrewlalisofficial@gmail.com>
Date: Mon, 12 Dec 2022 13:31:21 +0100
Subject: [PATCH] Added spi basic control.

---
 build.d   | 45 ++++++++++++++++++++++++++++++++++++++++-----
 src/spi.c | 32 ++++++++++++++++++++++++++++++++
 src/spi.h | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 105 insertions(+), 5 deletions(-)
 create mode 100644 src/spi.c
 create mode 100644 src/spi.h

diff --git a/build.d b/build.d
index 8bc6690..7826bed 100755
--- a/build.d
+++ b/build.d
@@ -9,6 +9,8 @@ import std.file;
 import std.string;
 import std.conv;
 import std.path;
+import std.digest.md;
+import std.base64;
 
 const string MCU_ID = "atmega328p";
 const ulong CPU_FREQ = 16_000_000;
@@ -28,7 +30,11 @@ int main(string[] args) {
         return build();
     }
     string command = args[1].strip.toLower;
-    if (command == "build") return build();
+    if (command == "flash") {
+        build().quitIfNonZero();
+        return flashToMCU(buildPath("bin", "gympal.hex"));
+    }
+    if (command == "build") return build(true);
     if (command == "clean") return clean();
 
     writefln!"Unknown command: \"%s\"."(command);
@@ -40,18 +46,18 @@ int clean() {
     return 0;
 }
 
-int build() {
+int build(bool force = false) {
     if (!exists(BUILD_DIR)) mkdir(BUILD_DIR);
     string[] sources = findFiles(SOURCE_DIR, ".c");
-    writefln!"Found %d source files."(sources.length);
     string[] objects;
     objects.reserve(sources.length);
     foreach (source; sources) {
-        objects ~= compileSourceToObject(source);
+        objects ~= compileSourceToObject(source, force);
     }
     string elfFile = linkObjects(objects);
     string hexFile = copyToHex(elfFile);
     writefln!"Built %s"(hexFile);
+    runOrQuit("avr-size " ~ hexFile);
     return 0;
 }
 
@@ -70,11 +76,34 @@ void runOrQuit(string shellCommand, int[] successExitCodes = [0]) {
     if (!canFind(successExitCodes, result)) exit(result);
 }
 
-string compileSourceToObject(string sourcePath) {
+void quitIfNonZero(int n) {
+    import core.stdc.stdlib : exit;
+    if (n != 0) exit(n);
+}
+
+bool shouldCompileSource(string sourcePath) {
+    string name = baseName(sourcePath);
+    name = name[0 .. name.lastIndexOf('.')];
+    string hashPath = buildPath("bin", "hash", name ~ ".md5");
+    string objectPath = buildPath("bin", name ~ ".o");
+    if (!exists(hashPath) || !exists(objectPath)) return true;
+    ubyte[] storedHash = Base64.decode(readText(hashPath).strip());
+    ubyte[16] currentHash = md5Of(readText(sourcePath));
+    return storedHash != currentHash;
+}
+
+string compileSourceToObject(string sourcePath, bool force = false) {
     string flags = join(COMPILER_FLAGS, " ");
     string name = baseName(sourcePath);
     name = name[0 .. name.lastIndexOf('.')];
     string objectPath = buildPath("bin", name ~ ".o");
+    string hashPath = buildPath("bin", "hash", name ~ ".md5");
+
+    if (!force && !shouldCompileSource(sourcePath)) {
+        writefln!"Not compiling %s because no changes detected."(sourcePath);
+        return objectPath;
+    }
+
     string cmd = format!"avr-gcc %s -DF_CPU=%dUL -mmcu=%s -c -o %s %s"(
         flags,
         CPU_FREQ,
@@ -84,6 +113,12 @@ string compileSourceToObject(string sourcePath) {
     );
     writeln(cmd);
     runOrQuit(cmd);
+
+    ubyte[16] hash = md5Of(readText(sourcePath));
+    string hashDir = buildPath("bin", "hash");
+    if (!exists(hashDir)) mkdir(hashDir);
+    std.file.write(hashPath, Base64.encode(hash));
+
     return objectPath;
 }
 
diff --git a/src/spi.c b/src/spi.c
new file mode 100644
index 0000000..bd2602d
--- /dev/null
+++ b/src/spi.c
@@ -0,0 +1,32 @@
+#include "spi.h"
+
+void spi_initMaster() {
+    SPI_DDR = (
+        (1 << SPI_MOSI) |
+        (1 << SPI_SCK)
+    );
+    SPCR = (
+        (1 << SPE) |
+        (1 << MSTR) |
+        (1 << SPR0)
+    );
+}
+
+void spi_initSlave() {
+    SPI_DDR = (1 << SPI_MISO);
+    SPCR = (1 << SPE);
+}
+
+void spi_masterTransmit(uint8_t data) {
+    SPDR = data;
+    while (!(SPSR & (1 << SPIF))) {
+        // Loop until we confirm transmission is done.
+    }
+}
+
+uint8_t spi_slaveReceive() {
+    while (!(SPSR & (1 << SPIF))) {
+        // Loop until SPI status is done.
+    }
+    return SPDR;
+}
\ No newline at end of file
diff --git a/src/spi.h b/src/spi.h
new file mode 100644
index 0000000..e069b34
--- /dev/null
+++ b/src/spi.h
@@ -0,0 +1,33 @@
+#ifndef SPI_H
+#define SPI_H
+
+#include <avr/io.h>
+
+#define SPI_DDR DDRB
+#define SPI_SCK DDB5
+#define SPI_MISO DDB4
+#define SPI_MOSI DDB3
+
+/**
+ * @brief Initializes this device as an SPI master.
+ */
+void spi_initMaster();
+
+/**
+ * @brief Initializes this device as an SPI slave. 
+ */
+void spi_initSlave();
+
+/** 
+ * @brief Transmits a single byte of data to the currently selected slave
+ * device. Blocks until transmission is complete.
+ */
+void spi_masterTransmit(uint8_t data);
+
+/**
+ * @brief Receives a single byte of data from a connected master. Blocks
+ * until the receive is complete.
+ */
+uint8_t spi_slaveReceive();
+
+#endif
\ No newline at end of file