format characters in qprintf() with optional length (r821) ported from volker_dev

git-svn-id: https://ssl.bulix.org/svn/lcd4linux/trunk@918 3ae390bd-cb1e-0410-b409-cd5a39f66f1f

qprintf.c

@@ -31,7 +31,9 @@
  * exported functions:
  * 
  * int qprintf(char *str, size_t size, const char *format, ...)
- *   works like snprintf(), but format only knows about %d and %s
+ *   works like snprintf(), but format only knows about %d, %x, %u and %s
+ *     and for the numbers an optional length like %<len>d. If <len> beginns
+ *     with '0' the free space is filled with '0's, otherwise with ' '
  */
 
 
@@ -42,7 +44,7 @@
 #include <stdarg.h>
 #include <string.h>
 
-static char *itoa(char *buffer, const size_t size, int value)
+static char *itoa(char *buffer, const size_t size, int value, unsigned int fixedlen, unsigned int fill0)
 {
     char *p;
     int sign;
@@ -55,6 +57,8 @@ static char *itoa(char *buffer, const size_t size, int value)
     sign = 0;
     if (value < 0) {
 	sign = 1;
+	if (fill0)
+	    fixedlen -= 1;
 	value = -value;
     }
 
@@ -69,14 +73,26 @@ static char *itoa(char *buffer, const size_t size, int value)
 	value = value / 10;
     } while (value != 0 && p > buffer);
 
-    if (sign && p > buffer)
+    if (sign && !fill0 && p > buffer)
+	*--p = '-';
+
+    /* fill fixed length */
+    while (p > buffer && strlen(p) < fixedlen) {
+	if (fill0) {
+	    *--p = '0';
+	} else {
+	    *--p = ' ';
+	}
+    }
+
+    if (sign && fill0 && p > buffer)
 	*--p = '-';
 
     return p;
 }
 
 
-static char *utoa(char *buffer, const size_t size, unsigned int value)
+static char *utoa(char *buffer, const size_t size, unsigned int value, unsigned int fixedlen, unsigned int fill0)
 {
     char *p;
 
@@ -95,11 +111,20 @@ static char *utoa(char *buffer, const size_t size, unsigned int value)
 	value = value / 10;
     } while (value != 0 && p > buffer);
 
+    /* fill fixed length */
+    while (p > buffer && strlen(p) < fixedlen) {
+	if (fill0) {
+	    *--p = '0';
+	} else {
+	    *--p = ' ';
+	}
+    }
+
     return p;
 }
 
 
-static char *utox(char *buffer, const size_t size, unsigned int value)
+static char *utox(char *buffer, const size_t size, unsigned int value, unsigned int fixedlen, unsigned int fill0)
 {
     char *p;
     int digit;
@@ -120,10 +145,29 @@ static char *utox(char *buffer, const size_t size, unsigned int value)
 	*--p = (digit < 10 ? '0' : 'a' - 10) + digit;
     } while (value != 0 && p > buffer);
 
+    /* fill fixed length */
+    while (p > buffer && strlen(p) < fixedlen) {
+	if (fill0) {
+	    *--p = '0';
+	} else {
+	    *--p = ' ';
+	}
+    }
+
     return p;
 }
 
 
+/*!
+    @function   qprintf
+    @abstract   quick print values into string
+    @discussion similar to snprintf(), but only support for "%s", "%d", "%u", "%x" with optional length for the numbers
+                like "%5d" (filled with ' ') or "%05x" (filled with '0')
+    @param      str  destination
+    @param      size  maximum length of destination string
+    @param      format  (like printf() with reduced number of formats)
+    @result     length of produced string
+*/
 int qprintf(char *str, const size_t size, const char *format, ...)
 {
 
@@ -145,7 +189,17 @@ int qprintf(char *str, const size_t size, const char *format, ...)
 	    char buf[12], *s;
 	    int d;
 	    unsigned int u;
-	    switch (*++src) {
+	    unsigned int fixedlen = 0;
+	    unsigned int fill0 = 0;
+
+	    if (*++src == '0')
+		fill0 = 1;
+	    while (*src >= '0' && *src <= '9') {
+		fixedlen = fixedlen * 10 + (*src - '0');
+		src++;
+	    }
+
+	    switch (*src) {
 	    case 's':
 		src++;
 		s = va_arg(ap, char *);
@@ -157,7 +211,7 @@ int qprintf(char *str, const size_t size, const char *format, ...)
 	    case 'd':
 		src++;
 		d = va_arg(ap, int);
-		s = itoa(buf, sizeof(buf), d);
+		s = itoa(buf, sizeof(buf), d, fixedlen, fill0);
 		while (len < size && *s != '\0') {
 		    len++;
 		    *dst++ = *s++;
@@ -166,7 +220,7 @@ int qprintf(char *str, const size_t size, const char *format, ...)
 	    case 'u':
 		src++;
 		u = va_arg(ap, unsigned int);
-		s = utoa(buf, sizeof(buf), u);
+		s = utoa(buf, sizeof(buf), u, fixedlen, fill0);
 		while (len < size - 1 && *s != '\0') {
 		    len++;
 		    *dst++ = *s++;
@@ -175,7 +229,7 @@ int qprintf(char *str, const size_t size, const char *format, ...)
 	    case 'x':
 		src++;
 		u = va_arg(ap, unsigned int);
-		s = utox(buf, sizeof(buf), u);
+		s = utox(buf, sizeof(buf), u, fixedlen, fill0);
 		while (len < size - 1 && *s != '\0') {
 		    len++;
 		    *dst++ = *s++;