printk: Refactor to allow passing a parsing context around

Pass a parsing context around, allowing counting the number of
characters written, which is then returned in the return value of
printk(). This makes printk more similar to printf and prepares the
way to extend the implementation to support printing to strings.

Change-Id: Ib28a18a4f36fc58b98b228fd5763b2c05f5af7bc
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

1 files changed, 48 insertions, 26 deletions

diff --git a/misc/printk.c b/misc/printk.c
index b8b5baf15..0bc4b95ff 100644
--- a/misc/printk.c
+++ b/misc/printk.c
@@ -27,9 +27,13 @@
 #include <toolchain.h>
 #include <sections.h>
 
-static void _printk_dec_ulong(const unsigned long num, int pad_zero,
+typedef int (*out_func_t)(int c, void *ctx);
+
+static void _printk_dec_ulong(out_func_t out, void *ctx,
+			      const unsigned long num, int pad_zero,
 			      int min_width);
-static void _printk_hex_ulong(const unsigned long num, int pad_zero,
+static void _printk_hex_ulong(out_func_t out, void *ctx,
+			      const unsigned long num, int pad_zero,
 			      int min_width);
 
 /**
@@ -48,7 +52,6 @@ static int _nop_char_out(int c)
 
 int (*_char_out)(int) = _nop_char_out;
 
-
 /**
  * @brief Install the character output routine for printk
  *
@@ -72,7 +75,8 @@ void __printk_hook_install(int (*fn)(int))
  *
  * @return N/A
  */
-static inline void _vprintk(const char *fmt, va_list ap)
+static inline void _vprintk(out_func_t out, void *ctx, const char *fmt,
+			    va_list ap)
 {
 	int might_format = 0; /* 1 if encountered a '%' */
 	int pad_zero = 0;
@@ -83,7 +87,7 @@ static inline void _vprintk(const char *fmt, va_list ap)
 	while (*fmt) {
 		if (!might_format) {
 			if (*fmt != '%') {
-				_char_out((int)*fmt);
+				out((int)*fmt, ctx);
 			} else {
 				might_format = 1;
 				min_width = -1;
@@ -114,22 +118,24 @@ static inline void _vprintk(const char *fmt, va_list ap)
 				long d = va_arg(ap, long);
 
 				if (d < 0) {
-					_char_out((int)'-');
+					out((int)'-', ctx);
 					d = -d;
 					min_width--;
 				}
-				_printk_dec_ulong(d, pad_zero, min_width);
+				_printk_dec_ulong(out, ctx, d, pad_zero,
+						  min_width);
 				break;
 			}
 			case 'u': {
 				unsigned long u = va_arg(
 					ap, unsigned long);
-				_printk_dec_ulong(u, pad_zero, min_width);
+				_printk_dec_ulong(out, ctx, u, pad_zero,
+						  min_width);
 				break;
 			}
 			case 'p':
-				  _char_out('0');
-				  _char_out('x');
+				  out('0', ctx);
+				  out('x', ctx);
 				  /* left-pad pointers with zeros */
 				  pad_zero = 1;
 				  min_width = 8;
@@ -138,29 +144,30 @@ static inline void _vprintk(const char *fmt, va_list ap)
 			case 'X': {
 				unsigned long x = va_arg(
 					ap, unsigned long);
-				_printk_hex_ulong(x, pad_zero, min_width);
+				_printk_hex_ulong(out, ctx, x, pad_zero,
+						  min_width);
 				break;
 			}
 			case 's': {
 				char *s = va_arg(ap, char *);
 
 				while (*s)
-					_char_out((int)(*s++));
+					out((int)(*s++), ctx);
 				break;
 			}
 			case 'c': {
 				int c = va_arg(ap, int);
 
-				_char_out(c);
+				out(c, ctx);
 				break;
 			}
 			case '%': {
-				_char_out((int)'%');
+				out((int)'%', ctx);
 				break;
 			}
 			default:
-				_char_out((int)'%');
-				_char_out((int)*fmt);
+				out((int)'%', ctx);
+				out((int)*fmt, ctx);
 				break;
 			}
 			might_format = 0;
@@ -170,6 +177,16 @@ still_might_format:
 	}
 }
 
+struct out_context {
+	int count;
+};
+
+static int char_out(int c, struct out_context *ctx)
+{
+	ctx->count++;
+	return _char_out(c);
+}
+
 /**
  * @brief Output a string
  *
@@ -186,15 +203,18 @@ still_might_format:
  *
  * @param fmt formatted string to output
  *
- * @return N/A
+ * @return Number of characters printed
  */
-void printk(const char *fmt, ...)
+int printk(const char *fmt, ...)
 {
+	struct out_context ctx = { 0 };
 	va_list ap;
 
 	va_start(ap, fmt);
-	_vprintk(fmt, ap);
+	_vprintk((out_func_t)char_out, &ctx, fmt, ap);
 	va_end(ap);
+
+	return ctx.count;
 }
 
 /**
@@ -206,7 +226,8 @@ void printk(const char *fmt, ...)
  *
  * @return N/A
  */
-static void _printk_hex_ulong(const unsigned long num, int pad_zero,
+static void _printk_hex_ulong(out_func_t out, void *ctx,
+			      const unsigned long num, int pad_zero,
 			      int min_width)
 {
 	int size = sizeof(num) * 2;
@@ -219,12 +240,12 @@ static void _printk_hex_ulong(const unsigned long num, int pad_zero,
 		if (nibble || found_largest_digit || size == 1) {
 			found_largest_digit = 1;
 			nibble += nibble > 9 ? 87 : 48;
-			_char_out((int)nibble);
+			out((int)nibble, ctx);
 			continue;
 		}
 
 		if (remaining-- <= min_width) {
-			_char_out((int)(pad_zero ? '0' : ' '));
+			out((int)(pad_zero ? '0' : ' '), ctx);
 		}
 	}
 }
@@ -238,7 +259,8 @@ static void _printk_hex_ulong(const unsigned long num, int pad_zero,
  *
  * @return N/A
  */
-static void _printk_dec_ulong(const unsigned long num, int pad_zero,
+static void _printk_dec_ulong(out_func_t out, void *ctx,
+			      const unsigned long num, int pad_zero,
 			      int min_width)
 {
 	unsigned long pos = 999999999;
@@ -254,14 +276,14 @@ static void _printk_dec_ulong(const unsigned long num, int pad_zero,
 	while (pos >= 9) {
 		if (found_largest_digit || remainder > pos) {
 			found_largest_digit = 1;
-			_char_out((int)((remainder / (pos + 1)) + 48));
+			out((int)((remainder / (pos + 1)) + 48), ctx);
 		} else if (remaining <= min_width) {
-			_char_out((int)(pad_zero ? '0' : ' '));
+			out((int)(pad_zero ? '0' : ' '), ctx);
 		}
 		remaining--;
 		remainder %= (pos + 1);
 		pos /= 10;
 	}
-	_char_out((int)(remainder + 48));
+	out((int)(remainder + 48), ctx);
 }