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2 Library Reference
AVR Libc Library Reference
2 <stdio.h>: Standard IO facilities
2.2 Functions
2.2.41 FILE* fdevopen
FILE* fdevopen(int(*put)(char, FILE *), int(*get)(FILE *))

AVRLibc

AVR Libc
1 User Manual
2 Library Reference
AVR Libc Library Reference
- 2 <alloca.h>: Allocate space in the stack
- 2 <assert.h>: Diagnostics
- 2 <avr/boot.h>: Bootloader Support Utilities
- 2 <avr/cpufunc.h>: Special AVR CPU functions
- 2 <avr/eeprom.h>: EEPROM handling
- 2 <avr/fuse.h>: Fuse Support
- 2 <avr/interrupt.h>: Interrupts
- 2 <avr/io.h>: AVR device-specific IO definitions
- 2 <avr/lock.h>: Lockbit Support
- 2 <avr/pgmspace.h>: Program Space Utilities
- 2 <avr/power.h>: Power Reduction Management
- 2 <avr/sfr_defs.h>: Special function registers
- 2 <avr/signature.h>: Signature Support
- 2 <avr/sleep.h>: Power Management and Sleep Modes
- 2 <avr/version.h>: avr-libc version macros
- 2 <avr/wdt.h>: Watchdog timer handling
- 2 <compat/deprecated.h>: Deprecated items
- 2 <compat/ina90.h>: Compatibility with IAR EWB 3.x
- 2 <ctype.h>: Character Operations
- 2 <errno.h>: System Errors
- 2 <inttypes.h>: Integer Type conversions
- 2 <math.h>: Mathematics
- 2 <setjmp.h>: Non-local goto
- 2 <stdint.h>: Standard Integer Types
- 2 <stdio.h>: Standard IO facilities
  - 2.1 Typedefs
  - 2.2 Functions
    - 2.2.1 int fclose
      int fclose(FILE *__stream)
    - 2.2.2 int vfprintf
      int vfprintf(FILE *__stream, const char *__fmt, va_list __ap)
    - 2.2.3 int vfprintf_P
      int vfprintf_P(FILE *__stream, const char *__fmt, va_list __ap)
    - 2.2.4 int fputc
      int fputc(int __c, FILE *__stream)
    - 2.2.5 int printf
      int printf(const char *__fmt,...)
    - 2.2.6 int printf_P
      int printf_P(const char *__fmt,...)
    - 2.2.7 int vprintf
      int vprintf(const char *__fmt, va_list __ap)
    - 2.2.8 int sprintf
      int sprintf(char *__s, const char *__fmt,...)
    - 2.2.9 int sprintf_P
      int sprintf_P(char *__s, const char *__fmt,...)
    - 2.2.10 int snprintf
      int snprintf(char *__s, size_t __n, const char *__fmt,...)
    - 2.2.11 int snprintf_P
      int snprintf_P(char *__s, size_t __n, const char *__fmt,...)
    - 2.2.12 int vsprintf
      int vsprintf(char *__s, const char *__fmt, va_list ap)
    - 2.2.13 int vsprintf_P
      int vsprintf_P(char *__s, const char *__fmt, va_list ap)
    - 2.2.14 int vsnprintf
      int vsnprintf(char *__s, size_t __n, const char *__fmt, va_list ap)
    - 2.2.15 int vsnprintf_P
      int vsnprintf_P(char *__s, size_t __n, const char *__fmt, va_list ap)
    - 2.2.16 int fprintf
      int fprintf(FILE *__stream, const char *__fmt,...)
    - 2.2.17 int fprintf_P
      int fprintf_P(FILE *__stream, const char *__fmt,...)
    - 2.2.18 int fputs
      int fputs(const char *__str, FILE *__stream)
    - 2.2.19 int fputs_P
      int fputs_P(const char *__str, FILE *__stream)
    - 2.2.20 int puts
      int puts(const char *__str)
    - 2.2.21 int puts_P
      int puts_P(const char *__str)
    - 2.2.22 size_t fwrite
      size_t fwrite(const void *__ptr, size_t __size, size_t __nmemb, FILE *__stream)
    - 2.2.23 int fgetc
      int fgetc(FILE *__stream)
    - 2.2.24 int ungetc
      int ungetc(int __c, FILE *__stream)
    - 2.2.25 char* fgets
      char* fgets(char *__str, int __size, FILE *__stream)
    - 2.2.26 char* gets
      char* gets(char *__str)
    - 2.2.27 size_t fread
      size_t fread(void *__ptr, size_t __size, size_t __nmemb, FILE *__stream)
    - 2.2.28 void clearerr
      void clearerr(FILE *__stream)
    - 2.2.29 int feof
      int feof(FILE *__stream)
    - 2.2.30 int ferror
      int ferror(FILE *__stream)
    - 2.2.31 int vfscanf
      int vfscanf(FILE *__stream, const char *__fmt, va_list __ap)
    - 2.2.32 int vfscanf_P
      int vfscanf_P(FILE *__stream, const char *__fmt, va_list __ap)
    - 2.2.33 int fscanf
      int fscanf(FILE *__stream, const char *__fmt,...)
    - 2.2.34 int fscanf_P
      int fscanf_P(FILE *__stream, const char *__fmt,...)
    - 2.2.35 int scanf
      int scanf(const char *__fmt,...)
    - 2.2.36 int scanf_P
      int scanf_P(const char *__fmt,...)
    - 2.2.37 int vscanf
      int vscanf(const char *__fmt, va_list __ap)
    - 2.2.38 int sscanf
      int sscanf(const char *__buf, const char *__fmt,...)
    - 2.2.39 int sscanf_P
      int sscanf_P(const char *__buf, const char *__fmt,...)
    - 2.2.40 int fflush
      int fflush(FILE *stream)
    - 2.2.41 FILE* fdevopen
      FILE* fdevopen(int(*put)(char, FILE *), int(*get)(FILE *))
  - 2.3 Defines
- 2 <stdlib.h>: General utilities
- 2 <string.h>: Strings
- 2 <time.h>: Time
- 2 <util/atomic.h> Atomically and Non-Atomically Executed Code Blocks
- 2 <util/crc16.h>: CRC Computations
- 2 <util/delay.h>: Convenience functions for busy-wait delay loops
- 2 <util/delay_basic.h>: Basic busy-wait delay loops
- 2 <util/parity.h>: Parity bit generation
- 2 <util/setbaud.h>: Helper macros for baud rate calculations
- 2 <util/twi.h>: TWI bit mask definitions
- 2.1 Structures
3 Example Projects
4 Files

2.2.41 FILE* fdevopen

FILE* fdevopen(int(*put)(char, FILE *), int(*get)(FILE *))

This function is a replacement for fopen().

It opens a stream for a device where the actual device implementation needs to be provided by the application. If successful, a pointer to the structure for the opened stream is returned. Reasons for a possible failure currently include that neither the put nor the get argument have been provided, thus attempting to open a stream with no IO intent at all, or that insufficient dynamic memory is available to establish a new stream.

If the put function pointer is provided, the stream is opened with write intent. The function passed as put shall take two arguments, the first a character to write to the device, and the second a pointer to FILE, and shall return 0 if the output was successful, and a nonzero value if the character could not be sent to the device.

If the get function pointer is provided, the stream is opened with read intent. The function passed as get shall take a pointer to FILE as its single argument, and return one character from the device, passed as an int type. If an error occurs when trying to read from the device, it shall return _FDEV_ERR. If an end-of-file condition was reached while reading from the device, _FDEV_EOF shall be returned.

If both functions are provided, the stream is opened with read and write intent.

The first stream opened with read intent is assigned to stdin, and the first one opened with write intent is assigned to both, stdout and stderr.

fdevopen() uses calloc() (und thus malloc()) in order to allocate the storage for the new stream.

Note:

If the macro __STDIO_FDEVOPEN_COMPAT_12 is declared before including <stdio.h>, a function prototype for fdevopen() will be chosen that is backwards compatible with avr-libc version 1.2 and before. This is solely intented for providing a simple migration path without the need to immediately change all source code. Do not use for new code.

The online versions of the documents are provided as a courtesy. Verify all content and data in the device’s PDF documentation found on the device product page.