Implement a leaner printf for Trusted Firmware

This patch implements a "tf_printf" which supports only the commonly
used format specifiers in Trusted Firmware, which uses a lot less
stack space than the stdlib printf function.

Fixes ARM-software/tf-issues#116

Change-Id: I7dfa1944f4c1e634b3e2d571f49afe02d109a351

1 files changed, 141 insertions, 0 deletions

diff --git a/common/tf_printf.c b/common/tf_printf.c
new file mode 100644
index 00000000..02461c0b
--- /dev/null
+++ b/common/tf_printf.c
@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <debug.h>
+#include <stdarg.h>
+#include <stdint.h>
+
+/***********************************************************
+ * The tf_printf implementation for all BL stages
+ ***********************************************************/
+static void unsigned_num_print(unsigned long int unum, unsigned int radix)
+{
+	/* Just need enough space to store 64 bit decimal integer */
+	unsigned char num_buf[20];
+	int i = 0 , rem;
+
+	do {
+		rem = unum % radix;
+		if (rem < 0xa)
+			num_buf[i++] = '0' + rem;
+		else
+			num_buf[i++] = 'a' + (rem - 0xa);
+	} while (unum /= radix);
+
+	while (--i >= 0)
+		putchar(num_buf[i]);
+}
+
+static void string_print(const char *str)
+{
+	while (*str)
+		putchar(*str++);
+}
+
+/*******************************************************************
+ * Reduced format print for Trusted firmware.
+ * The following formats are supported by this print
+ * %x - 32 bit hexadecimal format
+ * %llx and %lx -64 bit hexadecimal format
+ * %s - string format
+ * %d or %i - signed 32 bit decimal format
+ * %u - unsigned 32 bit decimal format
+ * %ld and %lld - signed 64 bit decimal format
+ * %lu and %llu - unsigned 64 bit decimal format
+ * Exits on all other formats.
+ *******************************************************************/
+
+void tf_printf(const char *fmt, ...)
+{
+	va_list args;
+	int bit64;
+	int64_t num;
+	uint64_t unum;
+	char *str;
+
+	va_start(args, fmt);
+	while (*fmt) {
+		bit64 = 0;
+
+		if (*fmt == '%') {
+			fmt++;
+			/* Check the format specifier */
+loop:
+			switch (*fmt) {
+			case 'i': /* Fall through to next one */
+			case 'd':
+				if (bit64)
+					num = va_arg(args, int64_t);
+				else
+					num = va_arg(args, int32_t);
+
+				if (num < 0) {
+					putchar('-');
+					unum = (unsigned long int)-num;
+				} else
+					unum = (unsigned long int)num;
+
+				unsigned_num_print(unum, 10);
+				break;
+			case 's':
+				str = va_arg(args, char *);
+				string_print(str);
+				break;
+			case 'x':
+				if (bit64)
+					unum = va_arg(args, uint64_t);
+				else
+					unum = va_arg(args, uint32_t);
+
+				unsigned_num_print(unum, 16);
+				break;
+			case 'l':
+				bit64 = 1;
+				fmt++;
+				goto loop;
+			case 'u':
+				if (bit64)
+					unum = va_arg(args, uint64_t);
+				else
+					unum = va_arg(args, uint32_t);
+
+				unsigned_num_print(unum, 10);
+				break;
+			default:
+				/* Exit on any other format specifier */
+				goto exit;
+			}
+			fmt++;
+			continue;
+		}
+		putchar(*fmt++);
+	}
+exit:
+	va_end(args);
+}