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Cross-platform C SDK

Standard I/O

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All processes have default input and output channels, without the need to create them explicitly.


Functions

uint32_tbstd_sprintf (...)
uint32_tbstd_vsprintf (...)
uint32_tbstd_printf (...)
uint32_tbstd_eprintf (...)
uint32_tbstd_writef (...)
uint32_tbstd_ewritef (...)
bool_tbstd_read (...)
bool_tbstd_write (...)
bool_tbstd_ewrite (...)
voidbstd_abort (void)
voidbstd_debug_break (void)

  • Use bstd_printf to write text to standard output.
  • Use bstd_read to read bytes from standard input.

Each running process has three standard communication channels:

  • stdin: data input. The process will read data that comes from outside.
  • stdout: data output. The process will write results on this channel.
  • stderr: error output. The process will write on this channel information regarding errors.

It's like having three perpetually open files where the program can read and write without limits. When we execute a process from the Console or the Terminal, stdin automatically connects to the keyboard and stdout/stderr to the screen (Figure 1). However, these standard channels can be redirected to use files as input sources or output destinations:

1
2
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dir > out.txt
ls > out.txt
sort < out.txt
Scheme showing the standard input/output channels of a process.
Figure 1: Executing a process from the Terminal.

In this code snippet, the result of the command dir (ls in Unix) has been redirected to the file out.txt, so we will not see anything on the screen. On the other hand, the command sort it does not wait for the user to enter through the keyboard. Simply taking the file out.txt, sorting its lines. Therefore, whenever we write applications on the command line, we should conveniently use these standard channels without making presumptions from where the information processed by the application comes from or where it goes.


bstd_sprintf ()

Write a string with the printf format in a memory buffer.

uint32_t
bstd_sprintf(char_t *str,
             const uint32_t size,
             const char_t *format,
             ...);
str

Pointer to the buffer where the result will be written. It will end in a null character '\0'.

size

Size of str in bytes.

format

String with the printf-like format with a variable number of parameters.

...

Arguments or variables of printf.

Return

The number of bytes written, not including the null character '\0'.

Remarks

It is a safe function and will not write more than size bytes. To obtain the necessary size of str, call this function with str=NULL and size=0.


bstd_vsprintf ()

Like bstd_sprintf but with the list of arguments already resolved.

uint32_t
bstd_vsprintf(char_t *str,
              const uint32_t size,
              const char_t *format,
              va_list args);
str

Pointer to the buffer where the result will be written. It will end in a null character '\0'.

size

Size of str in bytes.

format

String with the printf-like format with a variable number of parameters.

args

Arguments.

Return

The number of bytes written, not including the null character '\0'.

Remarks

It is a safe function and will not write more than size bytes.


bstd_printf ()

Writes a formatted string in the standard output (stdout). It is equivalent to the function printf from the standard library.

uint32_t
bstd_printf(const char_t *format,
            ...);
format

String with the printf-like format with a variable number of parameters.

...

Arguments or variables of printf.

Return

The number of bytes written in stdout.


bstd_eprintf ()

Writes a formatted string in the error output (stderr).

uint32_t
bstd_eprintf(const char_t *format,
             ...);
format

String with the printf-like format with a variable number of parameters.

...

Arguments or variables of printf.

Return

The number of bytes written in stderr.


bstd_writef ()

Write a string C UTF8 in the standard output (stdout).

uint32_t
bstd_writef(const char_t *str);
str

String C UTF8 ending in null character '\0'.

Return

The number of bytes written in stdout.


bstd_ewritef ()

Write a string C UTF8 on the error output (stderr).

uint32_t
bstd_ewritef(const char_t *str);
str

String C UTF8 ending in null character '\0'.

Return

The number of bytes written in stderr.


bstd_read ()

Read data from standard input stdin.

bool_t
bstd_read(byte_t *data,
          const uint32_t size,
          uint32_t *rsize);
data

Buffer where the read data will be written.

size

The number of maximum bytes to read (buffer size).

rsize

Receive the number of bytes actually read. Can be NULL.

Return

TRUE if data has been read. FALSE if any error has occurred.

Remarks

Standard stream implements high-level functions for reading/writing on standard channels.


bstd_write ()

Write data in the standard output stdout.

bool_t
bstd_write(const byte_t *data,
           const uint32_t size,
           uint32_t *wsize);
data

Buffer that contains the data to write.

size

The number of bytes to write.

wsize

It receives the number of bytes actually written. Can be NULL.

Return

TRUE if data has been written. FALSE if any error has occurred.

Remarks

Standard stream implements high-level functions for reading/writing on standard channels.


bstd_ewrite ()

Write data in the error output stderr.

bool_t
bstd_ewrite(const byte_t *data,
            const uint32_t size,
            uint32_t *wsize);
data

Buffer that contains the data to write.

size

The number of bytes to write.

wsize

It receives the number of bytes actually written. Can be NULL.

Return

TRUE if data has been written. FALSE if any error has occurred.

Remarks

Standard stream implements high-level functions for reading/writing on standard channels.


bstd_abort ()

The execution of the program ends abruptly.

void
bstd_abort(void);

Remarks

No resources are released or a controlled shutdown is performed. The only case where its use is justified is to exit the program after detecting an unrecoverable error (eg NULL pointer).


bstd_debug_break ()

Stops program execution at the point where the function is located and returns debugger control so we can inspect the stack, variables, etc.

void
bstd_debug_break(void);
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