[v5,14/19] printf: support field padding

Commit Message

Andrew Jones June 11, 2014, 2:01 p.m. UTC

Support format flags for field padding, such as "%08x", allowing
register dumps to be easier on the eyes.

Signed-off-by: Andrew Jones <[e-mail]>
Reviewed-by: Christoffer Dall <[e-mail]>
---
 lib/printf.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 68 insertions(+), 14 deletions(-)

Patch

diff --git a/lib/printf.c b/lib/printf.c
index 867eb1926f742..89308fb26b7d2 100644
--- a/lib/printf.c
+++ b/lib/printf.c
@@ -6,6 +6,11 @@  typedef struct pstream {
     int added;
 } pstream_t;
 
+typedef struct strprops {
+    char pad;
+    int npad;
+} strprops_t;
+
 static void addchar(pstream_t *p, char c)
 {
     if (p->remain) {
@@ -15,15 +20,35 @@  static void addchar(pstream_t *p, char c)
     ++p->added;
 }
 
-void print_str(pstream_t *p, const char *s)
+void print_str(pstream_t *p, const char *s, strprops_t props)
 {
+    const char *s_orig = s;
+    int npad = props.npad;
+
+    if (npad > 0) {
+	npad -= strlen(s_orig);
+	while (npad > 0) {
+	    addchar(p, props.pad);
+	    --npad;
+	}
+    }
+
     while (*s)
 	addchar(p, *s++);
+
+    if (npad < 0) {
+	props.pad = ' '; /* ignore '0' flag with '-' flag */
+	npad += strlen(s_orig);
+	while (npad < 0) {
+	    addchar(p, props.pad);
+	    ++npad;
+	}
+    }
 }
 
 static char digits[16] = "0123456789abcdef";
 
-void print_int(pstream_t *ps, long long n, int base)
+void print_int(pstream_t *ps, long long n, int base, strprops_t props)
 {
     char buf[sizeof(long) * 3 + 2], *p = buf;
     int s = 0, i;
@@ -54,10 +79,11 @@  void print_int(pstream_t *ps, long long n, int base)
 
     *p = 0;
 
-    print_str(ps, buf);
+    print_str(ps, buf, props);
 }
 
-void print_unsigned(pstream_t *ps, unsigned long long n, int base)
+void print_unsigned(pstream_t *ps, unsigned long long n, int base,
+		    strprops_t props)
 {
     char buf[sizeof(long) * 3 + 1], *p = buf;
     int i;
@@ -80,7 +106,23 @@  void print_unsigned(pstream_t *ps, unsigned long long n, int base)
 
     *p = 0;
 
-    print_str(ps, buf);
+    print_str(ps, buf, props);
+}
+
+static int fmtnum(const char **fmt)
+{
+    const char *f = *fmt;
+    int len = 0, num;
+
+    if (*f == '-')
+	++f, ++len;
+
+    while (*f >= '0' && *f <= '9')
+	++f, ++len;
+
+    num = atol(*fmt);
+    *fmt += len;
+    return num;
 }
 
 int vsnprintf(char *buf, int size, const char *fmt, va_list va)
@@ -93,6 +135,9 @@  int vsnprintf(char *buf, int size, const char *fmt, va_list va)
     while (*fmt) {
 	char f = *fmt++;
 	int nlong = 0;
+	strprops_t props;
+	memset(&props, 0, sizeof(props));
+	props.pad = ' ';
 
 	if (f != '%') {
 	    addchar(&s, f);
@@ -110,41 +155,50 @@  int vsnprintf(char *buf, int size, const char *fmt, va_list va)
 	case '\0':
 	    --fmt;
 	    break;
+	case '0':
+	    props.pad = '0';
+	    ++fmt;
+	    /* fall through */
+	case '1'...'9':
+	case '-':
+	    --fmt;
+	    props.npad = fmtnum(&fmt);
+	    goto morefmt;
 	case 'l':
 	    ++nlong;
 	    goto morefmt;
 	case 'd':
 	    switch (nlong) {
 	    case 0:
-		print_int(&s, va_arg(va, int), 10);
+		print_int(&s, va_arg(va, int), 10, props);
 		break;
 	    case 1:
-		print_int(&s, va_arg(va, long), 10);
+		print_int(&s, va_arg(va, long), 10, props);
 		break;
 	    default:
-		print_int(&s, va_arg(va, long long), 10);
+		print_int(&s, va_arg(va, long long), 10, props);
 		break;
 	    }
 	    break;
 	case 'x':
 	    switch (nlong) {
 	    case 0:
-		print_unsigned(&s, va_arg(va, unsigned), 16);
+		print_unsigned(&s, va_arg(va, unsigned), 16, props);
 		break;
 	    case 1:
-		print_unsigned(&s, va_arg(va, unsigned long), 16);
+		print_unsigned(&s, va_arg(va, unsigned long), 16, props);
 		break;
 	    default:
-		print_unsigned(&s, va_arg(va, unsigned long long), 16);
+		print_unsigned(&s, va_arg(va, unsigned long long), 16, props);
 		break;
 	    }
 	    break;
 	case 'p':
-	    print_str(&s, "0x");
-	    print_unsigned(&s, (unsigned long)va_arg(va, void *), 16);
+	    print_str(&s, "0x", props);
+	    print_unsigned(&s, (unsigned long)va_arg(va, void *), 16, props);
 	    break;
 	case 's':
-	    print_str(&s, va_arg(va, const char *));
+	    print_str(&s, va_arg(va, const char *), props);
 	    break;
 	default:
 	    addchar(&s, f);