Doxygenation

src/include/compiler.h

@@ -10,12 +10,21 @@
 #define __attribute__(x)
 #endif
 
-/*
- * We export the symbol obj_OBJECT (OBJECT is defined on command-line)
- * as a global symbol, so that the linker can drag in selected object
- * files from the library using -u obj_OBJECT.
+/** @file
  *
- * Not quite sure why cpp requires two levels of macro call in order
+ * Global compiler definitions.
+ *
+ * This file is implicitly included by every @c .c file in Etherboot.
+ * It defines global macros such as DBG() and ASSERT().
+ *
+ * We arrange for each object to export the symbol @c obj_OBJECT
+ * (where @c OBJECT is the object name, e.g. @c rtl8139) as a global
+ * symbol, so that the linker can drag in selected object files from
+ * the library using <tt> -u obj_OBJECT </tt>.
+ *
+ */
+
+/* Not quite sure why cpp requires two levels of macro call in order
  * to actually expand OBJECT...
  */
 #undef _H1
@@ -40,7 +49,9 @@
 __asm__ ( ".globl\t" OBJECT_SYMBOL_STR );
 __asm__ ( ".equ\t" OBJECT_SYMBOL_STR ", 0" );
 
-/*
+/**
+ * Drag in an object by object name.
+ *
  * Macro to allow objects to explicitly drag in other objects by
  * object name.  Used by config.c.
  *
@@ -48,6 +59,56 @@ __asm__ ( ".equ\t" OBJECT_SYMBOL_STR ", 0" );
 #define REQUIRE_OBJECT(object) \
 	__asm__ ( ".equ\tneed_" #object ", obj_" #object );
 
+/** @def DBG
+ *
+ * Print a debugging message.
+ *
+ * The debug level is set at build time by specifying the @c DEBUG=
+ * parameter on the @c make command line.  For example, to enable
+ * debugging for the PCI bus functions (in pci.c) in a @c .dsk image
+ * for the @c rtl8139 card, you could use the command line
+ *
+ * @code
+ *
+ *   make bin/rtl8139.dsk DEBUG=pci
+ *
+ * @endcode
+ *
+ * This will enable the debugging statements (DBG()) in pci.c.  If
+ * debugging is not enabled, DBG() statements will be ignored.
+ *
+ * You can enable debugging in several objects simultaneously by
+ * separating them with commas, as in
+ *
+ * @code
+ *
+ *   make bin/rtl8139.dsk DEBUG=pci,buffer,heap
+ *
+ * @endcode
+ *
+ * You can increase the debugging level for an object by specifying it
+ * with @c :N, where @c N is the level, as in
+ *
+ * @code
+ *
+ *   make bin/rtl8139.dsk DEBUG=pci,buffer:2,heap
+ *
+ * @endcode
+ *
+ * which would enable debugging for the PCI, buffer-handling and
+ * heap-allocation code, with the buffer-handling code at level 2.
+ *
+ */
+
+/** @def DBG2
+ *
+ * Print a level 2 debugging message.
+ *
+ * As for DBG().  DBG2() takes effect only when the debugging level is
+ * 2 or greater.
+ *
+ */
+
 /*
  * If debug_OBJECT is set to a true value, the macro DBG(...) will
  * expand to printf(...) when compiling OBJECT, and the symbol
@@ -77,8 +138,12 @@ __asm__ ( ".equ\tDEBUG_LEVEL, " DEBUG_SYMBOL_STR );
 #define DBG2 DBG_PRINT
 #endif
 
-/*
- * ASSERT() macros
+/**
+ * Assert a condition.
+ *
+ * If the condition is not true, a debug message will be printed.
+ * Assertions only take effect if the debug level is non-zero (see
+ * DBG()).
  *
  */
 #define ASSERT(x)
@@ -94,20 +159,35 @@ __asm__ ( ".equ\tDEBUG_LEVEL, " DEBUG_SYMBOL_STR );
 	} while (0)
 #endif
 
-/*
- * Commonly-used attributes.
+/** Declare a data structure as packed. */
+#define PACKED __attribute__ (( packed ))
+
+/** 
+ * Declare a variable or data structure as unused.
  *
- * Note that __used can be used only for functions.  If you have a
- * static variable declaration that you want to force to be included,
- * use __unused.
+ * Note that using @c __unused on a static global variable (such as a
+ * table structure as mentioned in tables.h) is necessary in order to
+ * inhibit compiler warnings.
  *
  */
-#define PACKED __attribute__ (( packed ))
 #define __unused __attribute__ (( unused ))
+
+/**
+ * Declare a function as used.
+ *
+ * Necessary only if the function is called only from assembler code.
+ * You cannot use this attribute for static global variables; use @c
+ * __unused instead.
+ *
+ */
 #define __used __attribute__ (( used ))
+
+/** Declare a data structure to be aligned with 16-byte alignment */
 #define __aligned __attribute__ (( aligned ( 16 ) ))
 
-/*
+/**
+ * Shared data.
+ *
  * To save space in the binary when multiple-driver images are
  * compiled, uninitialised data areas can be shared between drivers.
  * This will typically be used to share statically-allocated receive
@@ -115,13 +195,16 @@ __asm__ ( ".equ\tDEBUG_LEVEL, " DEBUG_SYMBOL_STR );
  *
  * Use as e.g.
  *
- *  struct {
+ * @code
+ *
+ *   struct {
  *	char	rx_buf[NUM_RX_BUF][RX_BUF_SIZE];
  *	char	tx_buf[TX_BUF_SIZE];
- *  } my_static_data __shared;
+ *   } my_static_data __shared;
+ *
+ * @endcode
  *
  */
-
 #define __shared __asm__ ( "_shared_bss" )
 
 #endif /* ASSEMBLY */