mbed-os/platform/source/minimal-printf/mbed_printf_implementation.c

682 lines
27 KiB
C

/* mbed Microcontroller Library
* Copyright (c) 2017-2020 ARM Limited
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mbed_printf_implementation.h"
#include <stdbool.h>
#include <limits.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#if !TARGET_LIKE_MBED
/* Linux implementation is for debug only */
#define MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_FLOATING_POINT 1
#define MBED_CONF_PLATFORM_MINIMAL_PRINTF_SET_FLOATING_POINT_MAX_DECIMALS 6
#define MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_64_BIT 1
#endif
#ifndef MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_FLOATING_POINT
#define MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_FLOATING_POINT 0
#endif
#ifndef MBED_CONF_PLATFORM_MINIMAL_PRINTF_SET_FLOATING_POINT_MAX_DECIMALS
#define MBED_CONF_PLATFORM_MINIMAL_PRINTF_SET_FLOATING_POINT_MAX_DECIMALS 6
#endif
#ifndef MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_64_BIT
#define MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_64_BIT 1
#endif
/**
* Check architecture and choose storage data type.
* On 32 bit machines, the default storage type is 32 bit wide
* unless 64 bit integers are enabled in the configuration.
*/
#if INTPTR_MAX == INT32_MAX
#define MBED_SIGNED_NATIVE_TYPE int32_t
#define MBED_UNSIGNED_NATIVE_TYPE uint32_t
#if MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_64_BIT
#define MBED_SIGNED_STORAGE int64_t
#define MBED_UNSIGNED_STORAGE uint64_t
#else
#define MBED_SIGNED_STORAGE int32_t
#define MBED_UNSIGNED_STORAGE uint32_t
#endif
#elif INTPTR_MAX == INT64_MAX
#define MBED_SIGNED_NATIVE_TYPE int64_t
#define MBED_UNSIGNED_NATIVE_TYPE uint64_t
#define MBED_SIGNED_STORAGE int64_t
#define MBED_UNSIGNED_STORAGE uint64_t
#else
#error unsupported architecture
#endif
/**
* Precision defines
*/
#define PRECISION_DEFAULT (INT_MAX)
/**
* Enum for storing width modifier.
*/
typedef enum {
LENGTH_NONE = 0x00,
LENGTH_H = 0x11,
LENGTH_L = 0x21,
LENGTH_J = 0x31,
LENGTH_Z = 0x41,
LENGTH_T = 0x51,
LENGTH_CAPITAL_L = 0x61,
LENGTH_HH = 0x72,
LENGTH_LL = 0x82
} length_t;
/**
* Enum for integer printing type
*/
typedef enum {
INT_UNSIGNED,
INT_SIGNED,
HEX_LOWER,
HEX_UPPER,
ZERO_NEGATIVE /* special case when printing integer part of double values where it is 0 and the value is negative */
} integer_type_t;
/**
* Prototypes
*/
static void mbed_minimal_formatted_string_integer(char *buffer, size_t length, int *result, MBED_UNSIGNED_STORAGE value, integer_type_t type, int width_size, bool prepend_zeros, FILE *stream);
static void mbed_minimal_formatted_string_void_pointer(char *buffer, size_t length, int *result, const void *value, FILE *stream);
static void mbed_minimal_formatted_string_string(char *buffer, size_t length, int *result, const char *string, size_t precision, FILE *stream);
/**
* @brief Print a single character, checking for buffer and size overflows.
*
* @param buffer The buffer to store output (NULL for stdout).
* @param[in] length The length of the buffer.
* @param result The current output location.
* @param[in] data The char to be printed.
*/
static void mbed_minimal_putchar(char *buffer, size_t length, int *result, char data, FILE *stream)
{
/* only continue if 'result' doesn't overflow */
if ((*result >= 0) && (*result <= INT_MAX - 1)) {
if (stream) {
if (fputc(data, stream) == EOF) {
*result = EOF;
} else {
*result += 1;
}
} else {
if (buffer) {
/* write data only if there's enough space */
if ((size_t)*result < length) {
buffer[*result] = data;
}
}
/* increment 'result' even if data was not written. This ensures that
'mbed_minimal_formatted_string' returns the correct value. */
*result += 1;
}
}
}
/**
* @brief Print integer in signed, unsigned or hexadecimal format.
*
* @param buffer The buffer to store output (NULL for stdout).
* @param[in] length The length of the buffer.
* @param result The current output location.
* @param[in] value The value to be printed.
* @param type The type of integer format that shall be printed (signed, unsigend or hexadecimal)
* @param width_size The width modifier.
* @param prepend_zeros Flag to prepends zeros when the width_size is greater than 0
*/
static void mbed_minimal_formatted_string_integer(char *buffer, size_t length, int *result, MBED_UNSIGNED_STORAGE value, integer_type_t type, int width_size, bool prepend_zeros, FILE *stream)
{
/* allocate 3 digits per byte */
char scratch[sizeof(MBED_UNSIGNED_STORAGE) * 3] = { 0 };
int index = 0;
bool negative_value = false;
const char filler = prepend_zeros ? '0' : ' ';
if (type == INT_SIGNED) {
if ((MBED_SIGNED_STORAGE) value < 0) {
/* get absolute value using two's complement */
value = ~value + 1;
negative_value = true;
}
} else if (type == ZERO_NEGATIVE) {
negative_value = true;
}
if (value == 0) {
scratch[index] = '0';
index++;
} else {
/* write numbers in reverse order to scratch pad */
for (; value > 0; index++) {
if (type == HEX_LOWER || type == HEX_UPPER) {
/* get least significant byte */
const uint8_t output = value & 0x0F;
static const char int2hex_lower[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};
static const char int2hex_upper[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
if (type == HEX_LOWER) {
scratch[index] = int2hex_lower[output];
} else {
scratch[index] = int2hex_upper[output];
}
/* shift value one byte position */
value = value >> 4;
} else {
/* use '0' as base and add digit */
scratch[index] = '0' + (value % 10);
/* shift value one decimal position */
value = value / 10;
}
}
}
if (negative_value) {
if (prepend_zeros) {
mbed_minimal_putchar(buffer, length, result, '-', stream);
}
index++; // add one to index to count '-'
}
// print filler characters
if (width_size > index) {
for (int i = width_size; i > index; i--) {
mbed_minimal_putchar(buffer, length, result, filler, stream);
}
}
if (negative_value) {
if (!prepend_zeros) {
mbed_minimal_putchar(buffer, length, result, '-', stream);
}
index--; // Restore index to correct position
}
/* print absolute value of integer */
for (; index > 0; index--) {
mbed_minimal_putchar(buffer, length, result, scratch[index - 1], stream);
}
}
/**
* @brief Print pointer.
*
* @param buffer The buffer to store output (NULL for stdout).
* @param[in] length The length of the buffer.
* @param result The current output location.
* @param[in] value The pointer to be printed.
*/
static void mbed_minimal_formatted_string_void_pointer(char *buffer, size_t length, int *result, const void *value, FILE *stream)
{
/* write leading 0x */
mbed_minimal_putchar(buffer, length, result, '0', stream);
mbed_minimal_putchar(buffer, length, result, 'x', stream);
/* write rest as a regular hexadecimal number */
mbed_minimal_formatted_string_integer(buffer, length, result, (ptrdiff_t) value, HEX_UPPER, 0, false, stream);
}
#if MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_FLOATING_POINT
/**
* @brief Write double.
*
* @param buffer The buffer to store output (NULL for stdout).
* @param[in] length The length of the buffer.
* @param result The current output location.
* @param[in] value The value to be printed.
* @param[in] dec_precision The decimal precision. If PRECISION_DEFAULT MBED_CONF_PLATFORM_MINIMAL_PRINTF_SET_FLOATING_POINT_MAX_DECIMALS is used.
* @param width_size The width modifier.
* @param prepend_zeros Flag to prepends zeros when the width_size is greater than 0
*/
static void mbed_minimal_formatted_string_double(char *buffer, size_t length, int *result, double value, int dec_precision, int width_size, bool prepend_zeros, FILE *stream)
{
/* get integer part */
MBED_SIGNED_STORAGE integer = value;
/* fractional part represented as the int that will be formatted after the dot, e.g. 95 for 1.95 */
MBED_SIGNED_STORAGE decimal = 0;
if (dec_precision == PRECISION_DEFAULT) {
dec_precision = MBED_CONF_PLATFORM_MINIMAL_PRINTF_SET_FLOATING_POINT_MAX_DECIMALS;
}
if (dec_precision != 0) {
/* get decimal part */
MBED_SIGNED_STORAGE precision = 1;
for (int index = 0; index < dec_precision; index++) {
precision *= 10;
}
/* Multiply the frac part so we get an int value with the required accuracy.
E.g. For 0.1234 and dec_precision=3 you'd get 123.4 */
double decimal_double = (value - integer) * precision;
if (value < 0) {
/* The part after the dot does not have a sign, so negate the value before rounding */
decimal = -decimal_double + 0.5;
if (decimal >= precision) {
/* Rounding carries over to value's integer part (e.g. -1.95 with dec_precision=1 -> -2.0) */
integer--;
decimal = 0;
}
} else {
/* Round the value */
decimal = decimal_double + 0.5;
if (decimal >= precision) {
/* Rounding carries over to value's integer part (e.g. 1.95 with dec_precision=1 -> 2.0) */
integer++;
decimal = 0;
}
}
width_size -= dec_precision + 1; // decimal precision plus '.'
if (width_size < 0) {
width_size = 0;
}
} else {
value = (value - integer) * 1.0;
if (value > 0.5) {
integer++;
} else if (value < -0.5) {
integer--;
}
}
/* write integer part */
if (integer == 0 && value < 0) {
mbed_minimal_formatted_string_integer(buffer, length, result, integer, ZERO_NEGATIVE, width_size, prepend_zeros, stream);
} else {
mbed_minimal_formatted_string_integer(buffer, length, result, integer, INT_SIGNED, width_size, prepend_zeros, stream);
}
if (dec_precision != 0) {
/* write decimal point */
mbed_minimal_putchar(buffer, length, result, '.', stream);
/* write decimal part */
mbed_minimal_formatted_string_integer(buffer, length, result, decimal, INT_UNSIGNED, dec_precision, true, stream);
}
}
#endif
/**
* @brief Print string with precision.
*
* @param buffer The buffer to store output (NULL for stdout).
* @param[in] length The length of the buffer.
* @param result The current output location.
* @param[in] value The string to be printed.
* @param[in] precision The maximum number of characters to be printed.
*/
static void mbed_minimal_formatted_string_string(char *buffer, size_t length, int *result, const char *string, size_t precision, FILE *stream)
{
while ((*string != '\0') && (precision)) {
mbed_minimal_putchar(buffer, length, result, *string, stream);
string++;
precision--;
}
}
/**
* @brief Parse a string to an integer value as long as there are numerical characters in the string
*
* @param[in] string The input string. Has to begin with a numerical character to parse
* @param[out] value The output value.
* @return size_t The number of numerical characters parsed
*/
static size_t parse_string_to_integer(const char *string, int *value)
{
size_t inner_index = 0;
while ((string[inner_index] >= '0') && (string[inner_index] <= '9')) {
*value = *value * 10 + (string[inner_index] - '0');
inner_index++;
}
return inner_index;
}
/**
* @brief Parse formatted string and invoke write handlers based on type.
*
* @param buffer The buffer to write to, write to stdout if NULL.
* @param[in] length The length of the buffer.
* @param[in] format The formatted string.
* @param[in] arguments The va_list arguments.
*
* @return Number of characters written.
*/
int mbed_minimal_formatted_string(char *buffer, size_t length, const char *format, va_list arguments, FILE *stream)
{
int result = 0;
bool empty_buffer = false;
/* ensure that function wasn't called with an empty buffer, or with or with
a buffer size that is larger than the maximum 'int' value, or with
a NULL format specifier */
if (format && length <= INT_MAX) {
/* Make sure that there's always space for the NULL terminator */
if (length > 0) {
length --;
} else {
/* the buffer is empty, there's no place to write the terminator */
empty_buffer = true;
}
/* parse string */
for (size_t index = 0; format[index] != '\0'; index++) {
/* format specifier begin */
if (format[index] == '%') {
size_t next_index = index + 1;
/**************************************************************
* skip and ignore flags [-+(space)#]
*************************************************************/
if ((format[next_index] == '-') ||
(format[next_index] == '+') ||
(format[next_index] == ' ') ||
(format[next_index] == '#')) {
/* skip to next character */
next_index++;
}
/**************************************************************
* look for width and prepending zeros [(number)], skip [*]
*************************************************************/
bool prepend_zeros = false;
int width_size = 0;
if (format[next_index] == '*') {
/* skip to next character */
next_index++;
/* discard argument */
va_arg(arguments, MBED_SIGNED_NATIVE_TYPE);
} else {
if (format[next_index] == '0') {
prepend_zeros = true;
do {
next_index++;
} while (format[next_index] == '0');
}
/* parse width modifier until not a decimal */
next_index += parse_string_to_integer(&format[next_index], &width_size);
}
/**************************************************************
* look for precision modifier
*************************************************************/
int precision = PRECISION_DEFAULT;
if ((format[next_index] == '.') &&
(format[next_index + 1] == '*')) {
next_index += 2;
/* read precision from argument list */
precision = va_arg(arguments, MBED_SIGNED_NATIVE_TYPE);
} else if (format[next_index] == '.') {
/* precision modifier found, reset default to 0 and increment index */
next_index++;
precision = 0;
/* parse precision until not a decimal */
next_index += parse_string_to_integer(&format[next_index], &precision);
}
/**************************************************************
* look for length modifier, default to NONE
*************************************************************/
length_t length_modifier = LENGTH_NONE;
/* look for two character length modifier */
if ((format[next_index] == 'h') && (format[next_index + 1] == 'h')) {
length_modifier = LENGTH_HH;
} else if ((format[next_index] == 'l') && (format[next_index + 1] == 'l')) {
length_modifier = LENGTH_LL;
}
/* look for one character length modifier if two character search failed */
else if (format[next_index] == 'h') {
length_modifier = LENGTH_H;
} else if (format[next_index] == 'l') {
length_modifier = LENGTH_L;
} else if (format[next_index] == 'j') {
length_modifier = LENGTH_J;
} else if (format[next_index] == 'z') {
length_modifier = LENGTH_Z;
} else if (format[next_index] == 't') {
length_modifier = LENGTH_T;
} else if (format[next_index] == 'L') {
length_modifier = LENGTH_CAPITAL_L;
}
/* increment index, length is encoded in modifier enum */
next_index += (length_modifier & 0x0F);
/**************************************************************
* read out character - this is a supported format character,
* '\0', or a not suported character
*************************************************************/
char next = format[next_index];
/* signed integer */
if ((next == 'd') || (next == 'i')) {
MBED_SIGNED_STORAGE value = 0;
#if MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_64_BIT
/* if 64 bit is enabled and the integer types are larger than the native type */
if (((length_modifier == LENGTH_LL) && (sizeof(long long int) > sizeof(MBED_SIGNED_NATIVE_TYPE))) ||
((length_modifier == LENGTH_L) && (sizeof(long int) > sizeof(MBED_SIGNED_NATIVE_TYPE))) ||
((length_modifier == LENGTH_NONE) && (sizeof(int) > sizeof(MBED_SIGNED_NATIVE_TYPE)))) {
/* use 64 bit storage type for readout */
value = va_arg(arguments, MBED_SIGNED_STORAGE);
} else
#else
/* If 64 bit is not enabled, print %ll[di] rather than truncated value */
if (length_modifier == LENGTH_LL) {
mbed_minimal_putchar(buffer, length, &result, '%', stream);
if (next == '%') {
// Continue printing loop after `%`
index = next_index;
}
continue;
}
#endif
{
/* use native storage type (which can be 32 or 64 bit) */
value = va_arg(arguments, MBED_SIGNED_NATIVE_TYPE);
}
/* constrict value based on length modifier */
switch (length_modifier) {
case LENGTH_NONE:
value = (int) value;
break;
case LENGTH_HH:
value = (signed char) value;
break;
case LENGTH_H:
value = (short int) value;
break;
case LENGTH_L:
value = (long int) value;
break;
case LENGTH_LL:
value = (long long int) value;
break;
case LENGTH_J:
value = (intmax_t) value;
break;
case LENGTH_T:
value = (ptrdiff_t) value;
break;
default:
break;
}
index = next_index;
mbed_minimal_formatted_string_integer(buffer, length, &result, value, INT_SIGNED, width_size, prepend_zeros, stream);
}
/* unsigned integer */
else if ((next == 'u') || (next == 'x') || (next == 'X')) {
MBED_UNSIGNED_STORAGE value = 0;
#if MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_64_BIT
/* if 64 bit is enabled and the integer types are larger than the native type */
if (((length_modifier == LENGTH_LL) && (sizeof(unsigned long long int) > sizeof(MBED_UNSIGNED_NATIVE_TYPE))) ||
((length_modifier == LENGTH_L) && (sizeof(unsigned long int) > sizeof(MBED_UNSIGNED_NATIVE_TYPE))) ||
((length_modifier == LENGTH_NONE) && (sizeof(unsigned int) > sizeof(MBED_UNSIGNED_NATIVE_TYPE)))) {
/* use 64 bit storage type for readout */
value = va_arg(arguments, MBED_UNSIGNED_STORAGE);
} else
#else
/* If 64 bit is not enabled, print %ll[uxX] rather than truncated value */
if (length_modifier == LENGTH_LL) {
mbed_minimal_putchar(buffer, length, &result, '%', stream);
if (next == '%') {
// Continue printing loop after `%`
index = next_index;
}
continue;
}
#endif
{
/* use native storage type (which can be 32 or 64 bit) */
value = va_arg(arguments, MBED_UNSIGNED_NATIVE_TYPE);
}
/* constrict value based on length modifier */
switch (length_modifier) {
case LENGTH_NONE:
value = (unsigned int) value;
break;
case LENGTH_HH:
value = (unsigned char) value;
break;
case LENGTH_H:
value = (unsigned short int) value;
break;
case LENGTH_L:
value = (unsigned long int) value;
break;
case LENGTH_LL:
value = (unsigned long long int) value;
break;
case LENGTH_J:
value = (uintmax_t) value;
break;
case LENGTH_Z:
value = (size_t) value;
break;
case LENGTH_T:
value = (ptrdiff_t) value;
break;
default:
break;
}
index = next_index;
/* write unsigned or hexadecimal */
if (next == 'u') {
mbed_minimal_formatted_string_integer(buffer, length, &result, value, INT_UNSIGNED, width_size, prepend_zeros, stream);
} else if (next == 'X') {
mbed_minimal_formatted_string_integer(buffer, length, &result, value, HEX_UPPER, width_size, prepend_zeros, stream);
} else {
mbed_minimal_formatted_string_integer(buffer, length, &result, value, HEX_LOWER, width_size, prepend_zeros, stream);
}
}
#if MBED_CONF_PLATFORM_MINIMAL_PRINTF_ENABLE_FLOATING_POINT
/* treat all floating points the same */
else if ((next == 'f') || (next == 'F') || (next == 'g') || (next == 'G')) {
double value = va_arg(arguments, double);
index = next_index;
mbed_minimal_formatted_string_double(buffer, length, &result, value, precision, width_size, prepend_zeros, stream);
}
#endif
/* character */
else if (next == 'c') {
char value = va_arg(arguments, MBED_SIGNED_NATIVE_TYPE);
index = next_index;
mbed_minimal_putchar(buffer, length, &result, value, stream);
}
/* string */
else if (next == 's') {
char *value = va_arg(arguments, char *);
index = next_index;
mbed_minimal_formatted_string_string(buffer, length, &result, value, precision, stream);
}
/* pointer */
else if (next == 'p') {
void *value = va_arg(arguments, void *);
index = next_index;
mbed_minimal_formatted_string_void_pointer(buffer, length, &result, value, stream);
} else {
// Unrecognised, or `%%`. Print the `%` that led us in.
mbed_minimal_putchar(buffer, length, &result, '%', stream);
if (next == '%') {
// Continue printing loop after `%%`
index = next_index;
}
// Otherwise we continue the printing loop after the leading `%`, so an
// unrecognised thing like "Blah = %a" will just come out as "Blah = %a"
}
} else
/* not a format specifier */
{
/* write normal character */
mbed_minimal_putchar(buffer, length, &result, format[index], stream);
}
}
if (buffer && !empty_buffer) {
/* NULL-terminate the buffer no matter what. We use '<=' to compare instead of '<'
because we know that we initially reserved space for '\0' by decrementing length */
if ((size_t)result <= length) {
buffer[result] = '\0';
} else {
buffer[length] = '\0';
}
}
}
return result;
}