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da5241cb15
This is a reduced version of `snprintf` that only supports formats '%d', '%i' and '%u'. It can be used when the full `snprintf` is not needed in order to save memory. If it finds an unknown format specifier, it prints an error message and panics. Change-Id: I2cb06fcdf74cda2c43caf73ae0762a91499fc04e Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
109 lines
2.3 KiB
C
109 lines
2.3 KiB
C
/*
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* Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <debug.h>
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#include <platform.h>
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#include <stdarg.h>
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static void unsigned_dec_print(char **s, size_t n, size_t *chars_printed,
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unsigned int unum)
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{
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/* Enough for a 32-bit unsigned decimal integer (4294967295). */
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unsigned char num_buf[10];
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int i = 0, rem;
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do {
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rem = unum % 10;
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num_buf[i++] = '0' + rem;
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} while (unum /= 10);
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while (--i >= 0) {
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if (*chars_printed < n)
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*(*s)++ = num_buf[i];
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(*chars_printed)++;
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}
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}
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/*******************************************************************
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* Reduced snprintf to be used for Trusted firmware.
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* The following type specifiers are supported:
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*
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* %d or %i - signed decimal format
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* %u - unsigned decimal format
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*
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* The function panics on all other formats specifiers.
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*
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* It returns the number of characters that would be written if the
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* buffer was big enough. If it returns a value lower than n, the
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* whole string has been written.
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*******************************************************************/
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int tf_snprintf(char *s, size_t n, const char *fmt, ...)
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{
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va_list args;
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int num;
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unsigned int unum;
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size_t chars_printed = 0;
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if (n == 1) {
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/* Buffer is too small to actually write anything else. */
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*s = '\0';
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n = 0;
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} else if (n >= 2) {
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/* Reserve space for the terminator character. */
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n--;
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}
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va_start(args, fmt);
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while (*fmt) {
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if (*fmt == '%') {
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fmt++;
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/* Check the format specifier. */
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switch (*fmt) {
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case 'i':
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case 'd':
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num = va_arg(args, int);
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if (num < 0) {
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if (chars_printed < n)
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*s++ = '-';
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chars_printed++;
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unum = (unsigned int)-num;
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} else {
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unum = (unsigned int)num;
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}
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unsigned_dec_print(&s, n, &chars_printed, unum);
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break;
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case 'u':
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unum = va_arg(args, unsigned int);
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unsigned_dec_print(&s, n, &chars_printed, unum);
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break;
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default:
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/* Panic on any other format specifier. */
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ERROR("tf_snprintf: specifier with ASCII code '%d' not supported.",
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*fmt);
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plat_panic_handler();
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}
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fmt++;
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continue;
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}
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if (chars_printed < n)
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*s++ = *fmt;
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fmt++;
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chars_printed++;
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}
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va_end(args);
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if (n > 0)
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*s = '\0';
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return chars_printed;
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}
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