lib/tiny-printf.c: Add tiny printf function for space limited environments

This patch adds a small printf() version that supports all basic formats.
Its intented to be used in U-Boot SPL versions on platforms with very
limited internal RAM sizes.

To enable it, just define CONFIG_USE_TINY_PRINTF in your defconfig. This
will result in the SPL using this tiny function and the main U-Boot
still using the full-blown printf() function.

This code was copied from:
http://www.sparetimelabs.com/printfrevisited
With mostly only coding style related changes so that its checkpatch
clean.

The size reduction is about 2.5KiB. Here a comparison for the db-mv784mp-gp
(Marvell AXP) SPL:

Without this patch:
  58963   18536    1928   79427   13643 ./spl/u-boot-spl

With this patch:
  56542   18536    1956   77034   12cea ./spl/u-boot-spl

Note:
To make it possible to compile tiny-printf.c instead of vsprintf.c when
CONFIG_USE_TINY_PRINTF is defined, the functions printf() and vprintf() are
moved from common/console.c into vsprintf.c in this patch.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>

common/console.c

@@ -558,42 +558,6 @@ void puts(const char *s)
 	}
 }
 
-int printf(const char *fmt, ...)
-{
-	va_list args;
-	uint i;
-	char printbuffer[CONFIG_SYS_PBSIZE];
-
-	va_start(args, fmt);
-
-	/*
-	 * For this to work, printbuffer must be larger than
-	 * anything we ever want to print.
-	 */
-	i = vscnprintf(printbuffer, sizeof(printbuffer), fmt, args);
-	va_end(args);
-
-	/* Print the string */
-	puts(printbuffer);
-	return i;
-}
-
-int vprintf(const char *fmt, va_list args)
-{
-	uint i;
-	char printbuffer[CONFIG_SYS_PBSIZE];
-
-	/*
-	 * For this to work, printbuffer must be larger than
-	 * anything we ever want to print.
-	 */
-	i = vscnprintf(printbuffer, sizeof(printbuffer), fmt, args);
-
-	/* Print the string */
-	puts(printbuffer);
-	return i;
-}
-
 #ifdef CONFIG_CONSOLE_RECORD
 int console_record_init(void)
 {

examples/api/libgenwrap.c

@@ -16,46 +16,14 @@
 
 #include "glue.h"
 
-/*
- * printf() and vprintf() are stolen from u-boot/common/console.c
- */
-int printf (const char *fmt, ...)
-{
-	va_list args;
-	uint i;
-	char printbuffer[256];
-
-	va_start (args, fmt);
-
-	/* For this to work, printbuffer must be larger than
-	 * anything we ever want to print.
-	 */
-	i = vsprintf (printbuffer, fmt, args);
-	va_end (args);
-
-	/* Print the string */
-	ub_puts (printbuffer);
-	return i;
-}
-
-int vprintf (const char *fmt, va_list args)
+void putc(const char c)
 {
-	uint i;
-	char printbuffer[256];
-
-	/* For this to work, printbuffer must be larger than
-	 * anything we ever want to print.
-	 */
-	i = vsprintf (printbuffer, fmt, args);
-
-	/* Print the string */
-	ub_puts (printbuffer);
-	return i;
+	ub_putc(c);
 }
 
-void putc (const char c)
+void puts(const char *s)
 {
-	ub_putc(c);
+	ub_puts(s);
 }
 
 void __udelay(unsigned long usec)

lib/Kconfig

@@ -36,6 +36,16 @@ config SYS_VSNPRINTF
 	  Thumb-2, about 420 bytes). Enable this option for safety when
 	  using sprintf() with data you do not control.
 
+config USE_TINY_PRINTF
+	bool "Enable tiny printf() version"
+	help
+	  This option enables a tiny, stripped down printf version.
+	  This should only be used in space limited environments,
+	  like SPL versions with hard memory limits. This version
+	  reduces the code size by about 2.5KiB on armv7.
+
+	  The supported format specifiers are %c, %s, %u/%d and %x.
+
 config REGEX
 	bool "Enable regular expression support"
 	default y if NET

lib/Makefile

@@ -80,7 +80,18 @@ obj-y += string.o
 obj-y += time.o
 obj-$(CONFIG_TRACE) += trace.o
 obj-$(CONFIG_LIB_UUID) += uuid.o
-obj-y += vsprintf.o
 obj-$(CONFIG_LIB_RAND) += rand.o
 
+ifdef CONFIG_SPL_BUILD
+# SPL U-Boot may use full-printf, tiny-printf or none at all
+ifdef CONFIG_USE_TINY_PRINTF
+obj-$(CONFIG_SPL_SERIAL_SUPPORT) += tiny-printf.o
+else
+obj-$(CONFIG_SPL_SERIAL_SUPPORT) += vsprintf.o
+endif
+else
+# Main U-Boot always uses the full printf support
+obj-y += vsprintf.o
+endif
+
 subdir-ccflags-$(CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED) += -O2

lib/tiny-printf.c

@@ -0,0 +1,130 @@
+/*
+ * Tiny printf version for SPL
+ *
+ * Copied from:
+ * http://www.sparetimelabs.com/printfrevisited/printfrevisited.php
+ *
+ * Copyright (C) 2004,2008  Kustaa Nyholm
+ *
+ * SPDX-License-Identifier:	LGPL-2.1+
+ */
+
+#include <common.h>
+#include <stdarg.h>
+#include <serial.h>
+
+static char *bf;
+static char buf[12];
+static unsigned int num;
+static char uc;
+static char zs;
+
+static void out(char c)
+{
+	*bf++ = c;
+}
+
+static void out_dgt(char dgt)
+{
+	out(dgt + (dgt < 10 ? '0' : (uc ? 'A' : 'a') - 10));
+	zs = 1;
+}
+
+static void div_out(unsigned int div)
+{
+	unsigned char dgt = 0;
+
+	num &= 0xffff; /* just for testing the code with 32 bit ints */
+	while (num >= div) {
+		num -= div;
+		dgt++;
+	}
+
+	if (zs || dgt > 0)
+		out_dgt(dgt);
+}
+
+int printf(const char *fmt, ...)
+{
+	va_list va;
+	char ch;
+	char *p;
+
+	va_start(va, fmt);
+
+	while ((ch = *(fmt++))) {
+		if (ch != '%') {
+			putc(ch);
+		} else {
+			char lz = 0;
+			char w = 0;
+
+			ch = *(fmt++);
+			if (ch == '0') {
+				ch = *(fmt++);
+				lz = 1;
+			}
+
+			if (ch >= '0' && ch <= '9') {
+				w = 0;
+				while (ch >= '0' && ch <= '9') {
+					w = (((w << 2) + w) << 1) + ch - '0';
+					ch = *fmt++;
+				}
+			}
+			bf = buf;
+			p = bf;
+			zs = 0;
+
+			switch (ch) {
+			case 0:
+				goto abort;
+			case 'u':
+			case 'd':
+				num = va_arg(va, unsigned int);
+				if (ch == 'd' && (int)num < 0) {
+					num = -(int)num;
+					out('-');
+				}
+				div_out(10000);
+				div_out(1000);
+				div_out(100);
+				div_out(10);
+				out_dgt(num);
+				break;
+			case 'x':
+			case 'X':
+				uc = ch == 'X';
+				num = va_arg(va, unsigned int);
+				div_out(0x1000);
+				div_out(0x100);
+				div_out(0x10);
+				out_dgt(num);
+				break;
+			case 'c':
+				out((char)(va_arg(va, int)));
+				break;
+			case 's':
+				p = va_arg(va, char*);
+				break;
+			case '%':
+				out('%');
+			default:
+				break;
+			}
+
+			*bf = 0;
+			bf = p;
+			while (*bf++ && w > 0)
+				w--;
+			while (w-- > 0)
+				putc(lz ? '0' : ' ');
+			while ((ch = *p++))
+				putc(ch);
+		}
+	}
+
+abort:
+	va_end(va);
+	return 0;
+}

lib/vsprintf.c

@@ -861,6 +861,42 @@ int sprintf(char *buf, const char *fmt, ...)
 	return i;
 }
 
+int printf(const char *fmt, ...)
+{
+	va_list args;
+	uint i;
+	char printbuffer[CONFIG_SYS_PBSIZE];
+
+	va_start(args, fmt);
+
+	/*
+	 * For this to work, printbuffer must be larger than
+	 * anything we ever want to print.
+	 */
+	i = vscnprintf(printbuffer, sizeof(printbuffer), fmt, args);
+	va_end(args);
+
+	/* Print the string */
+	puts(printbuffer);
+	return i;
+}
+
+int vprintf(const char *fmt, va_list args)
+{
+	uint i;
+	char printbuffer[CONFIG_SYS_PBSIZE];
+
+	/*
+	 * For this to work, printbuffer must be larger than
+	 * anything we ever want to print.
+	 */
+	i = vscnprintf(printbuffer, sizeof(printbuffer), fmt, args);
+
+	/* Print the string */
+	puts(printbuffer);
+	return i;
+}
+
 static void panic_finish(void) __attribute__ ((noreturn));
 
 static void panic_finish(void)