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

661 lines
26 KiB
C

/* mbed Microcontroller Library
* Copyright (c) 2017 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>
/***************************/
/* MBED */
/***************************/
#if TARGET_LIKE_MBED
#if MBED_CONF_PLATFORM_STDIO_CONVERT_NEWLINES
static char mbed_stdio_out_prev = 0;
#endif
/***************************/
/* Linux */
/***************************/
#else
/* 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;
/**
* Prototypes
*/
static void mbed_minimal_formatted_string_signed(char *buffer, size_t length, int *result, MBED_SIGNED_STORAGE value, FILE *stream);
static void mbed_minimal_formatted_string_unsigned(char *buffer, size_t length, int *result, MBED_UNSIGNED_STORAGE value, FILE *stream);
static void mbed_minimal_formatted_string_hexadecimal(char *buffer, size_t length, int *result, MBED_UNSIGNED_STORAGE value, FILE *stream, bool upper);
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_character(char *buffer, size_t length, int *result, char character, 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)) {
/* write data only if there's enough space */
if ((size_t)*result < length) {
if (buffer) {
buffer[*result] = data;
} else {
fputc(data, stream);
}
}
/* increment 'result' even if data was not written. This ensures that
'mbed_minimal_formatted_string' returns the correct value. */
*result += 1;
}
}
/**
* @brief Print signed integer.
*
* @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.
*/
static void mbed_minimal_formatted_string_signed(char *buffer, size_t length, int *result, MBED_SIGNED_STORAGE value, FILE *stream)
{
MBED_UNSIGNED_STORAGE new_value = 0;
/* if value is negative print sign and treat as positive number */
if (value < 0) {
/* write sign */
mbed_minimal_putchar(buffer, length, result, '-', stream);
/* get absolute value using two's complement */
new_value = ~((MBED_UNSIGNED_STORAGE) value) + 1;
} else {
new_value = value;
}
/* use unsigned long int function */
mbed_minimal_formatted_string_unsigned(buffer, length, result, new_value, stream);
}
/**
* @brief Print unsigned integer.
*
* @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.
*/
static void mbed_minimal_formatted_string_unsigned(char *buffer, size_t length, int *result, MBED_UNSIGNED_STORAGE value, FILE *stream)
{
/* treat 0 as a corner case */
if (value == 0) {
mbed_minimal_putchar(buffer, length, result, '0', stream);
} else {
/* allocate 3 digits per byte */
char scratch[sizeof(MBED_UNSIGNED_STORAGE) * 3] = { 0 };
size_t index = 0;
/* write numbers in reverse order to scratch pad */
for (; value > 0; index++) {
/* use '0' as base and add digit */
scratch[index] = '0' + (value % 10);
/* shift value one decimal position */
value = value / 10;
}
/* write scratch pad to buffer or output */
for (; index > 0; index--) {
mbed_minimal_putchar(buffer, length, result, scratch[index - 1], stream);
}
}
}
/**
* @brief Print hexadecimal.
*
* @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 upper Flag to print the hexadecimal in upper or lower case.
*/
static void mbed_minimal_formatted_string_hexadecimal(char *buffer, size_t length, int *result, MBED_UNSIGNED_STORAGE value, FILE *stream, bool upper)
{
bool print_leading_zero = false;
for (int index = 7; index >= 0; index--) {
/* get most significant byte */
uint8_t output = value >> (8 * index);
/* only print leading zeros when set */
if (print_leading_zero || (output != 0) || (index == 0)) {
unsigned int nibble_one = (output >> 4);
unsigned int nibble_two = (output & 0x0F);
const char int2hex_lower[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};
const char int2hex_upper[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
const char *int2hex = upper ? int2hex_upper : int2hex_lower;
if (print_leading_zero || nibble_one != 0) {
mbed_minimal_putchar(buffer, length, result, int2hex[nibble_one], stream);
}
mbed_minimal_putchar(buffer, length, result, int2hex[nibble_two], stream);
/* print zeroes after the first non-zero byte */
print_leading_zero = true;
}
}
}
/**
* @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_hexadecimal(buffer, length, result, (ptrdiff_t) value, stream, true);
}
#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.
*/
static void mbed_minimal_formatted_string_double(char *buffer, size_t length, int *result, double value, FILE *stream)
{
/* get integer part */
MBED_SIGNED_STORAGE integer = value;
/* write integer part */
mbed_minimal_formatted_string_signed(buffer, length, result, integer, stream);
/* write decimal point */
mbed_minimal_formatted_string_character(buffer, length, result, '.', stream);
/* get decimal part */
double precision = 1.0;
for (size_t index = 0; index < MBED_CONF_PLATFORM_MINIMAL_PRINTF_SET_FLOATING_POINT_MAX_DECIMALS; index++) {
precision *= 10;
}
value = (value - integer) * precision;
/* convert to unsigned integer */
MBED_UNSIGNED_STORAGE decimal = 0;
if (value < 0) {
MBED_SIGNED_STORAGE temp = value;
decimal = ~((MBED_UNSIGNED_STORAGE) temp) + 1;
} else {
decimal = value;
}
/* round up or down */
value -= decimal;
if (!((value > -0.5) && (value < 0.5))) {
decimal++;
}
/* convert precision to unsigned integer */
MBED_UNSIGNED_STORAGE precision_in_uint = precision;
precision_in_uint /= 10;
/* ensure that leading zeros are printed if decimal equals 0 */
MBED_UNSIGNED_STORAGE val = decimal ? decimal : decimal + 1;
while (precision_in_uint > val) {
/* print leading zeros */
mbed_minimal_putchar(buffer, length, result, '0', stream);
precision_in_uint /= 10;
}
/* write decimal part */
mbed_minimal_formatted_string_unsigned(buffer, length, result, decimal, stream);
}
#endif
/**
* @brief Print character.
*
* @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 character to be printed.
*/
static void mbed_minimal_formatted_string_character(char *buffer, size_t length, int *result, char character, FILE *stream)
{
/* write character */
if (buffer) {
mbed_minimal_putchar(buffer, length, result, character, stream);
} else {
/* convert \n to \r\n if enabled in platform configuration */
#if MBED_CONF_PLATFORM_STDIO_CONVERT_NEWLINES
if (character == '\n' && mbed_stdio_out_prev != '\r') {
mbed_minimal_putchar(buffer, length, result, '\r', stream);
}
/* cache character */
mbed_stdio_out_prev = character;
#endif
mbed_minimal_putchar(buffer, length, result, character, stream);
}
}
/**
* @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 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)#0]
*************************************************************/
if ((format[next_index] == '-') ||
(format[next_index] == '+') ||
(format[next_index] == ' ') ||
(format[next_index] == '#') ||
(format[next_index] == '0')) {
/* skip to next character */
next_index++;
}
/**************************************************************
* skip and ignore width [(number)*]
*************************************************************/
if (format[next_index] == '*') {
/* skip to next character */
next_index++;
/* discard argument */
va_arg(arguments, MBED_SIGNED_NATIVE_TYPE);
} else {
while ((format[next_index] >= '0') &&
(format[next_index] <= '9')) {
/* skip to next character */
next_index++;
}
}
/**************************************************************
* 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 */
size_t inner_index = 0;
while ((format[next_index + inner_index] >= '0') &&
(format[next_index + inner_index] <= '9')) {
precision = precision * 10 + (format[next_index + inner_index] - '0');
inner_index++;
}
/* move index forward to point at next character */
next_index += inner_index;
}
/**************************************************************
* 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
#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_signed(buffer, length, &result, value, 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
#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_unsigned(buffer, length, &result, value, stream);
} else {
mbed_minimal_formatted_string_hexadecimal(buffer, length, &result, value, stream, next == 'X');
}
}
#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, stream);
}
#endif
/* character */
else if (next == 'c') {
char value = va_arg(arguments, MBED_SIGNED_NATIVE_TYPE);
index = next_index;
mbed_minimal_formatted_string_character(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_formatted_string_character(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_formatted_string_character(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;
}