Merge pull request #4 from akriese/feature/glue-serial-printf

feat: glue serial i/o and printf

Makefile

@@ -16,7 +16,7 @@
 # Quellen
 #
 LSCRIPT = kernel.lds
-OBJ = start.o serial.o
+OBJ = start.o serial.o printf.o
 
 #
 # Konfiguration

printf.c

@@ -0,0 +1,93 @@
+#include <stdarg.h> // for va_list etc., can be imported, as not OS specific
+
+#include "serial.h"
+
+#define HEX_POSITIONS 8 // 1 hex char represents 4 bits; assuming 32bit integers
+
+/*
+ * Some function that actually prints a character or sends it via the serial
+ * interface
+ */
+void _print(char c) { serial_write(c); }
+
+void _printChar(const char c);
+void _printString(const char *s);
+void _printHex(const int u);
+void _printAddress(const void *p);
+
+/*
+ * Our printf implementation
+ *
+ */
+__attribute__((format(printf, 1, 2))) void printf(const char *fmt, ...) {
+  va_list arguments;
+
+  va_start(arguments, fmt);
+
+  while (*fmt) {
+    if (*fmt != '%') {
+      _print(*fmt);
+      fmt++;
+      continue;
+    }
+
+    char f = *(++fmt);
+
+    // in case there is a trailing '%'
+    if (!f) {
+      _print('%');
+      break;
+    }
+
+    switch (f) {
+    case 'c':
+      _printChar((char)va_arg(arguments, int));
+      break;
+    case 's':
+      _printString(va_arg(arguments, char *));
+      break;
+    case 'x':
+      _printHex(va_arg(arguments, int));
+      break;
+    case 'p':
+      _printAddress(va_arg(arguments, void *));
+      break;
+    default:
+      _printString("Invalid formatter!");
+    }
+
+    fmt++;
+  }
+
+  va_end(arguments);
+}
+
+void _printChar(const char c) { _print(c); }
+
+void _printString(const char *s) {
+  while (*s) {
+    _print(*s++);
+  }
+}
+
+char _singleHex(int u) {
+  if (u < 10)
+    return '0' + u;
+  return 'a' + u - 10;
+}
+
+void _printHex(const int u) {
+  char hex[HEX_POSITIONS + 1]; // including trailing null terminator
+
+  hex[HEX_POSITIONS] = '\0';
+
+  for (int i = 0; i < HEX_POSITIONS; ++i) {
+    char res = _singleHex(u >> (i * 4) & 0xF);
+    hex[HEX_POSITIONS - i - 1] = res;
+  }
+
+  // using the string formatting of our own printf to prepend the "0x"
+  printf("0x%s", hex);
+}
+
+void _printAddress(const void *p) { _printHex((int)p); }

printf.h

@@ -1,96 +1,2 @@
-/*
-
-*/
-
-#include <stdarg.h> // for va_list etc
-
-#define HEX_POSITIONS 8 // 1 hex char represents 4 bits; assuming 32bit integers
-
-/*
- * Some function that actually prints a character or sends it via the serial
- * interface
- */
-void _print(char c);
-
-void _printChar(const char c);
-void _printString(const char *s);
-void _printHex(const int u);
-void _printAddress(const void *p);
-
-/*
- * Our printf implementation
- *
- */
-__attribute__((format(printf, 1, 2)))
-void print(const char *fmt, ...) {
-  va_list arguments;
-
-  va_start(arguments, fmt);
-
-  while (*fmt) {
-    if (*fmt != '%') {
-      _print(*fmt);
-      fmt++;
-      continue;
-    }
-
-    char f = *(++fmt);
-
-    // in case there is a trailing '%'
-    if (!f) {
-      _print('%');
-      break;
-    }
-
-    switch (f) {
-    case 'c':
-      _printChar((char)va_arg(arguments, int));
-      break;
-    case 's':
-      _printString(va_arg(arguments, char *));
-      break;
-    case 'x':
-      _printHex(va_arg(arguments, int));
-      break;
-    case 'p':
-      _printAddress(va_arg(arguments, void *));
-      break;
-    default:
-      _printString("Invalid formatter!");
-    }
-
-    fmt++;
-  }
-
-  va_end(arguments);
-}
-
-void _printChar(const char c) { _print(c); }
-
-void _printString(const char *s) {
-  while (*s) {
-    _print(*s++);
-  }
-}
-
-char _singleHex(int u) {
-  if (u < 10)
-    return '0' + u;
-  return 'a' + u - 10;
-}
-
-void _printHex(const int u) {
-  char hex[HEX_POSITIONS + 1]; // including trailing null terminator
-
-  hex[HEX_POSITIONS] = '\0';
-
-  for (int i = 0; i < HEX_POSITIONS; ++i) {
-    char res = _singleHex(u >> (i * 4) & 0xF);
-    hex[HEX_POSITIONS - i - 1] = res;
-  }
-
-  // using the string formatting of our own printf to prepend the "0x"
-  print("0x%s", hex);
-}
-
-void _printAddress(const void *p) { _printHex((int)p); }
+// prints a string with format identifiers and variable arguments
+void printf(const char *fmt, ...);

serial.c

@@ -45,7 +45,7 @@ void write_char(char c) { *(volatile char *)DBGU_THR = c; }
  * There is no need to clear the register or signal anything after reading,
  * as that is done by the controller upon the register read instruction.
  */
-char read() {
+char serial_read() {
   // enable receive controller
   set_status(DBGU_CR, RXEN_BIT);
 
@@ -66,7 +66,7 @@ char read() {
  *
  * The controller has to be enabled before and disabled afterwards.
  */
-void write(char c) {
+void serial_write(char c) {
   // enable write controller
   set_status(DBGU_CR, TXEN_BIT);
 
@@ -89,7 +89,7 @@ void write(char c) {
  * disabled afterwards, but not inbetween, as multiple characters can be sent in
  * a row.
  */
-void write_string(char *s) {
+void serial_write_string(char *s) {
   // enable write controller
   set_status(DBGU_CR, TXEN_BIT);
 

serial.h

@@ -1,9 +1,8 @@
 // Reads a char from the serial interface
-char read();
+char serial_read();
 
 // Writes a char to the serial interface
-void write(char c);
+void serial_write(char c);
 
 // Writes a string to the serial interface. Stops at the first \0 in s
-void write_string(char *s);
-
+void serial_write_string(char *s);

start.c

@@ -1,24 +1,22 @@
 // include what you want to execute
+#include "printf.h"
 #include "serial.h"
 
 __attribute__((naked, section(".init"))) void _start(void) {
   // execute your os here
-  write_string("Type a character and shrineOS will translate it!\n\r");
-  write_string("Terminate the OS with 'q'!\n\r");
+  printf("Type a character and shrineOS will translate it!\n\r");
+  printf("Terminate the OS with 'q'!\n\r");
 
   for (;;) {
-    char c = read();
-    write_string("You gave the char: ");
-    write(c);
+    char c = serial_read();
+    printf("You gave the char: %c\n\r", c);
 
     if (c == 'q') {
-      write_string("\n\rAnd now, I'll terminate myself...");
+      printf("And now, I'll terminate myself...\n\r");
       break;
     }
 
-    write_string("\n\rshrineOS says: ");
-    write(c + 1);
-    write_string("\n\r");
+    printf("shrineOS says: %c\n\r", c + 1);
   }
 
   // then use an endless loop (for now)