[libc] Allow for zero-padded decimals in printf()

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/core/vsprintf.c b/src/core/vsprintf.c
index b46d9c4191711cf11722e863c3df0e8a11bf8425..b838b89e536725233caeee8e2209f2f0f1835534 100644 (file)
--- a/src/core/vsprintf.c
+++ b/src/core/vsprintf.c
@@ -60,12 +60,21 @@ static uint8_t type_sizes[] = {
  */
 #define ALT_FORM 0x02
 
+/**
+ * Use zero padding
+ *
+ * Note that this value is set to 0x10 since that allows the pad
+ * character to be calculated as @c 0x20|(flags&ZPAD)
+ */
+#define ZPAD 0x10
+
 /**
  * Format a hexadecimal number
  *
  * @v end              End of buffer to contain number
  * @v num              Number to format
  * @v width            Minimum field width
+ * @v flags            Format flags
  * @ret ptr            End of buffer
  *
  * Fills a buffer in reverse order with a formatted hexadecimal
@@ -79,18 +88,18 @@ static uint8_t type_sizes[] = {
 static char * format_hex ( char *end, unsigned long long num, int width,
                           int flags ) {
        char *ptr = end;
-       int case_mod;
+       int case_mod = ( flags & LCASE );
+       int pad = ( ( flags & ZPAD ) | ' ' );
 
        /* Generate the number */
-       case_mod = flags & LCASE;
        do {
                *(--ptr) = "0123456789ABCDEF"[ num & 0xf ] | case_mod;
                num >>= 4;
        } while ( num );
 
-       /* Zero-pad to width */
+       /* Pad to width */
        while ( ( end - ptr ) < width )
-               *(--ptr) = '0';
+               *(--ptr) = pad;
 
        /* Add "0x" or "0X" if alternate form specified */
        if ( flags & ALT_FORM ) {
@@ -107,6 +116,7 @@ static char * format_hex ( char *end, unsigned long long num, int width,
  * @v end              End of buffer to contain number
  * @v num              Number to format
  * @v width            Minimum field width
+ * @v flags            Format flags
  * @ret ptr            End of buffer
  *
  * Fills a buffer in reverse order with a formatted decimal number.
@@ -115,9 +125,12 @@ static char * format_hex ( char *end, unsigned long long num, int width,
  * There must be enough space in the buffer to contain the largest
  * number that this function can format.
  */
-static char * format_decimal ( char *end, signed long num, int width ) {
+static char * format_decimal ( char *end, signed long num, int width,
+                              int flags ) {
        char *ptr = end;
        int negative = 0;
+       int zpad = ( flags & ZPAD );
+       int pad = ( zpad | ' ' );
 
        /* Generate the number */
        if ( num < 0 ) {
@@ -130,12 +143,16 @@ static char * format_decimal ( char *end, signed long num, int width ) {
        } while ( num );
 
        /* Add "-" if necessary */
-       if ( negative )
+       if ( negative && ( ! zpad ) )
                *(--ptr) = '-';
 
-       /* Space-pad to width */
+       /* Pad to width */
        while ( ( end - ptr ) < width )
-               *(--ptr) = ' ';
+               *(--ptr) = pad;
+
+       /* Add "-" if necessary */
+       if ( negative && zpad )
+               *ptr = '-';
 
        return ptr;
 }
@@ -186,7 +203,7 @@ size_t vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
                        if ( *fmt == '#' ) {
                                flags |= ALT_FORM;
                        } else if ( *fmt == '0' ) {
-                               /* We always 0-pad hex and space-pad decimal */
+                               flags |= ZPAD;
                        } else {
                                /* End of flag characters */
                                break;
@@ -250,7 +267,7 @@ size_t vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
                        } else {
                                decimal = va_arg ( args, signed int );
                        }
-                       ptr = format_decimal ( ptr, decimal, width );
+                       ptr = format_decimal ( ptr, decimal, width, flags );
                } else {
                        *(--ptr) = *fmt;
                }