Rewrite buffer related stuff to avoid weird stack overflow(?) issues

firmware/src/commands.c

@@ -103,14 +103,12 @@ void commandRead(char* arg) {
 
     uartPutLine("OK");
 
-    uint8_t byteBuffer[DATA_BLOCK_SIZE];
-    DataBuffer buffer = {
-        .data = byteBuffer,
-        .maxSize = DATA_BLOCK_SIZE,
-        .bytes = 0
-    };
+    // Create data buffer
+    DataBuffer buffer;
 
     do {
+        buffer.bytes = 0;
+
         // Read a single block with up to DATA_BLOCK_SIZE bytes
         Address nextAddress = eepromReadBlock(range, &buffer);
         range.isValid = nextAddress.isValid;
@@ -121,16 +119,16 @@ void commandRead(char* arg) {
             // First the size of the package (1 byte) followed by the data bytes
             uartPutChar(buffer.bytes);
 
-            for (int i = 0; i < buffer.bytes; i++) {
+            for (uint8_t i = 0; i < buffer.bytes; i++) {
                 uartPutChar(buffer.data[i]);
             }
         } else {
             // Fancy ASCII output
-            uartPutChar('<');
-            uartPutInteger(buffer.bytes);
+            uartPutString("<0x");
+            uartPutHexByte(buffer.bytes);
             uartPutChar('>');
 
-            for (int i = 0; i < buffer.bytes; i++) {
+            for (uint8_t i = 0; i < buffer.bytes; i++) {
                 uartPutChar(' ');
                 uartPutHexByte(buffer.data[i]);
             }
@@ -159,17 +157,12 @@ void commandWrite(char* arg) {
         return;
     }
 
-    // Create data buffer
-    uint8_t byteBuffer[DATA_BLOCK_SIZE];
-    DataBuffer buffer = {
-        .data = byteBuffer,
-        .maxSize = DATA_BLOCK_SIZE,
-        .bytes = 0
-    };
-
     // "OK" indicates that data can be sent now.
     uartPutLine("OK START");
 
+    // Create data buffer
+    DataBuffer buffer;
+
     Address currentAddress = startAddress;
     uint8_t block_length = 0;
 
@@ -180,10 +173,8 @@ void commandWrite(char* arg) {
         // Read and check block length
         block_length = uartGetChar();
 
-        if (block_length > buffer.maxSize) {
-            uartPutString("ERROR maximal block size is: ");
-            uartPutInteger(buffer.maxSize);
-            uartPutLine(NULL);
+        if (block_length > DATA_BLOCK_SIZE) {
+            uartPutLine("ERROR maximal block size is: " STR(DATA_BLOCK_SIZE));
             return;
         }
 
@@ -196,9 +187,6 @@ void commandWrite(char* arg) {
         if (buffer.bytes > 0) {
             currentAddress = eepromWriteBlock(currentAddress, buffer);
 
-            // TODO wait necessary?
-            //_delay_ms(100);
-
             if (!currentAddress.isValid) {
                 uartPutLine("ERROR reached end of EEPROM while writing block");
                 return;

firmware/src/common.h

@@ -8,6 +8,10 @@
 // Define macro for NOP instruction
 #define _NOP() __asm__ __volatile__ ("nop");
 
+// Define macro to convert a preprocessor constant to a string literal
+#define STR_(x) #x
+#define STR(x) STR_(x)
+
 // Define type for EEPROM addresses
 typedef uint16_t address_t;
 
@@ -28,12 +32,11 @@ typedef struct {
 } AddressRange;
 
 // Define type for a block of data (bytes)
+#define DATA_BLOCK_SIZE 64
+
 typedef struct {
-    uint8_t* data;
-    uint8_t maxSize;
+    uint8_t data[DATA_BLOCK_SIZE];
     uint8_t bytes;
 } DataBuffer;
 
-#define DATA_BLOCK_SIZE 64
-
 #endif /* COMMON_H_ */

firmware/src/eeprom.c

@@ -132,7 +132,7 @@ Address eepromReadBlock(AddressRange addressRange, DataBuffer* buffer) {
         highestAddress = HIGHEST_VALID_ADDRESS;
     }
 
-    while (currentAddress <= highestAddress && buffer->bytes < buffer->maxSize) {
+    while (currentAddress <= highestAddress && buffer->bytes < DATA_BLOCK_SIZE) {
         buffer->data[buffer->bytes++] = eepromReadByte(currentAddress++);
 
         // Handle integer overflow

firmware/src/parsing.c

@@ -13,7 +13,7 @@
 
 // Read and parse command line and dispatch command
 void parseNextCommand() {
-    const int bufferLength = 80;
+    const int bufferLength = 40;
     char buffer[bufferLength];
 
     // Read next command

firmware/src/uart.c

@@ -4,8 +4,15 @@
 #include <avr/io.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <util/setbaud.h>
 
+// Hexadecimal digit lookup table
+static const char hexDigitLookupTable[] = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
+};
+
 // Initialize UART
 void uartInit() {
     // Set Baud register
@@ -56,18 +63,12 @@ void uartPutLine(char* data) {
     uartPutChar('\n');
 }
 
-// Convert an integer to decimal ASCII and transmit
-void uartPutInteger(int value) {
-    char outBuffer[32];
-    snprintf(outBuffer, 32, "%d", value);
-    uartPutString(outBuffer);
-}
-
 // Convert a byte to hexadecimal ASCII and transmit
 void uartPutHexByte(uint8_t byte) {
-    char outBuffer[8];
-    snprintf(outBuffer, 8, "%02hhX", byte);
-    uartPutString(outBuffer);
+    // First hex digit: most significant 4 bits
+    uartPutChar(hexDigitLookupTable[(byte >> 4) & 0x0f]);
+    // Second hex digit: least significant 4 bits
+    uartPutChar(hexDigitLookupTable[byte & 0x0f]);
 }
 
 // Receive a single character (blocking)

firmware/src/uart.h

@@ -16,9 +16,6 @@ void uartPutString(char* data);
 // Transmit a string followed by a line break
 void uartPutLine(char* data);
 
-// Convert an integer to decimal ASCII and transmit
-void uartPutInteger(int value);
-
 // Convert a byte to hexadecimal ASCII and transmit
 void uartPutHexByte(uint8_t byte);