/* 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 #include #include #include #include #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; }