4 #include <stdio.h> /* for FILE typedef*/
5 #include <stdint.h> /* for uint16_t, uint32_t */
9 /* Read/write "x" from/to "file" as bigendian representation of "size" bits.
10 * Only multiples of 8 allowed for "size". On failure, return 1, else 0.
12 * As of of now, all other read/write functions build on top of these. TODO:
13 * Consider externing these so-far internal functions and dropping the
14 * interfaces to them, instead relying on their internal validity checks.
15 * (Usage of padded memory copies instead of directly manipulating * x as is
16 * done in read_uint* would need to be added, though.)
18 static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size);
19 static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size);
23 static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size)
25 if (0 != size % 8) /* This bit number validity check is redundant */
26 { /* as long as this function is only available */
27 return 1; /* through extern interfaces pre-defining the */
28 } /* bit number. TODO: Consider dropping it. */
29 int16_t bitshift = size - 8;
33 for (; bitshift >= 0; bitshift = bitshift - 8)
40 * x = * x + ((uint32_t) test << bitshift);
47 static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size)
49 if (0 != size % 8) /* See comment */
51 return 1; /* code block in */
52 } /* read_uintX_bigendian(). */
53 int16_t bitshift = size - 8;
55 for (; bitshift >= 0; bitshift = bitshift - 8)
57 if (EOF == fputc((x >> bitshift) & 0xFF, file))
67 extern uint8_t read_uint8(FILE * file, uint8_t * x)
69 /* Since read_uintX_bigendian() works on -- and zeroes -- four bytes, direct
70 * work on values of fewer bytes would corrupt immediate neighbor values.
73 uint8_t err = read_uintX_bigendian(file, &y, 8);
80 extern uint8_t read_uint16_bigendian(FILE * file, uint16_t * x)
82 /* See read_uint8() introductory comment for rationale. */
84 uint8_t err = read_uintX_bigendian(file, &y, 16);
91 extern uint8_t read_uint32_bigendian(FILE * file, uint32_t * x)
93 return read_uintX_bigendian(file, x, 32);
98 extern uint8_t write_uint8(uint8_t x, FILE * file)
100 return write_uintX_bigendian(file, x, 8);
105 extern uint8_t write_uint16_bigendian(uint16_t x, FILE * file)
107 return write_uintX_bigendian(file, x, 16);
112 extern uint8_t write_uint32_bigendian(uint32_t x, FILE * file)
114 return write_uintX_bigendian(file, x, 32);