gp_io_parser.h File Reference

Commmon functions to parse data. More...

#include <loaders/gp_io.h>

Go to the source code of this file.

Enumerations
enum	gp_io_fmt_types {   GP_IO_CONST = 0x0000 , GP_IO_BYTE = 0x0100 , GP_IO_L2 = 0x0200 , GP_IO_L4 = 0x0300 ,   GP_IO_B2 = 0x0400 , GP_IO_B4 = 0x0500 , GP_IO_ARRAY = 0x0600 , GP_IO_IGN = 0x0700 ,   GP_IO_I1 = GP_IO_IGN | 1 , GP_IO_I2 = GP_IO_IGN | 2 , GP_IO_I3 = GP_IO_IGN | 3 , GP_IO_I4 = GP_IO_IGN | 4 ,   GP_IO_PPSTR = 0x0800 , GP_IO_END = 0xff00 }
	Formatted binary read and write types. More...

Functions
int	gp_io_readf (gp_io *self, const uint16_t *types,...)
	Parses a data accodingly to the array of types.
int	gp_io_writef (gp_io *self, const uint16_t *types,...)
	Writes a data accodingly to the array of types.
int	gp_io_read_b4 (gp_io *self, uint32_t *val)
	Reads a single 32bit big endian integer.
int	gp_io_read_b2 (gp_io *self, uint16_t *val)
	Reads a single 16bit big endian integer.
char *	gp_io_read_b2_utf16 (gp_io *io, size_t nchars)
	Reads unicode string stored in big endian utf16 format.

Detailed Description

Commmon functions to parse data.

Definition in file gp_io_parser.h.

Enumeration Type Documentation

gp_io_fmt_types

enum gp_io_fmt_types

Formatted binary read and write types.

This interface is a bit similar to a printf and scanf but instead of format string we have an array of 16bit unsigned integers describing the data.

Enumerator
GP_IO_CONST	A constant byte in lower half of the 16bit integer. Since this is defined as a zero values less than or equal to 0xff are interpreted as constant bytes and matched or written exactly.
GP_IO_BYTE	Reads or writes a single byte.
GP_IO_L2	Reads or writes two bytes in a little endian order. The bytes are read or written into the corresponding pionter as a 16bit integer in a machine endinanity.
GP_IO_L4	Reads or writes four bytes in a little endian order. The bytes are read or written into the corresponding pionter as a 32bit integer in a machine endinanity.
GP_IO_B2	Reads or writes two bytes in a big endian order. The bytes are read or written into the corresponding pionter as a 16bit integer in a machine endinanity.
GP_IO_B4	Reads or writes four bytes in a big endian order. The bytes are read or written into the corresponding pionter as a 32bit integer in a machine endinanity.
GP_IO_ARRAY	Pointer to byte array, size in lower half.
GP_IO_IGN	Ignore bytes on read, size in lower half.
GP_IO_I1	Ignore single byte on read.
GP_IO_I2	Ignore two bytes on read.
GP_IO_I3	Ignore three bytes on read.
GP_IO_I4	Ignore four bytes on read.
GP_IO_PPSTR	A photoshop pascal string. First byte stores size and string is padded to even number bytes. The lower half stores passed buffer size. TODO: Unfinished
GP_IO_END	End of the types array. This is terminating entry for the array.

Definition at line 22 of file gp_io_parser.h.

Function Documentation

gp_io_read_b2()

int gp_io_read_b2	(	gp_io *	self,
		uint16_t *	val )

Reads a single 16bit big endian integer.

The integer is read as a big endian from the I/O and stored into the ppointer in the machine endianity.

Parameters

self	A readable I/O.
val	A pointer to store the integer value into.

Returns

Zero on success non-zero otherwise.

gp_io_read_b2_utf16()

char * gp_io_read_b2_utf16	(	gp_io *	io,
		size_t	nchars )

Reads unicode string stored in big endian utf16 format.

Parameters

io	A readable I/O.
nbytes	Number of characters, the number of bytes is twice the number of the characters for utf16.

Returns

A newly allocated null terminated utf8 string or NULL in a case of a allocation failure.

gp_io_read_b4()

int gp_io_read_b4	(	gp_io *	self,
		uint32_t *	val )

Reads a single 32bit big endian integer.

The integer is read as a big endian from the I/O and stored into the ppointer in the machine endianity.

Parameters

self	A readable I/O.
val	A pointer to store the integer value into.

Returns

Zero on success non-zero otherwise.

gp_io_readf()

int gp_io_readf	(	gp_io *	self,
		const uint16_t *	types,
			... )

Parses a data accodingly to the array of types.

Example usage:

uint16_t ihdr_size, width, height;
 
const uint16_t png_header[] = {
   0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n',
   GP_IO_B4, // IHDR size
   'I', 'H', 'D', 'R',
   GP_IO_B4, // Width
   GP_IO_B4, // Height
   GP_IO_END,
};
 
int ret = gp_io_readf(io, png_header, &ihdr_size, &width, &height);
 
if (ret != ARRAY_SIZE(png_header) - 1) {
   //error
}
 
printf("PNG image size %ux%u\n", (unsigned int)width, (unsigned int)height);

Parameters

self	A readable I/O.
types	An array of enum gp_io_fmt_types terminated by GP_IO_END describing the values to be read.
...	Pointers to data describes in the types array.

Returns

A number of read types or -1 in a case of a failure.

gp_io_writef()

int gp_io_writef	(	gp_io *	self,
		const uint16_t *	types,
			... )

Writes a data accodingly to the array of types.

Example usage:

uint16_t bitmap_header[] = {
   'B', 'M',               // signature
   GP_IO_L4,               // offset to pixels
   0x00, 0x00, 0x00, 0x00, // reserved
   GP_IO_L4,               // file size
   GP_IO_END,
};
 
if (gp_io_writef(io, bitmap_header, file_size, pixel_offset))
   return EIO;

Parameters

self	A writeable I/O.
types	An array of enum gp_io_fmt_types terminated by GP_IO_END describing the values to be written.
...	Pointers to data describes in the types array.

Returns

A zero on success.