4 #include <stdio.h> /* for FILE typedef*/
5 #include <stdint.h> /* for uint8_t, uint16_t, uint32_t */
9 /* Read/write "x" from/to "file" as bigendian representation of "size" bits. On
10 * failure, return 1, else 0. (As of of now, all extern read/write functions
11 * build on top of these.)
13 * Only use multiples of 8 greater or equal 32 for "size", so that storage
14 * inside uint32_t is possible. Originally a bit number check prefaced the code
15 * of both functions. It was removed as redundant due to all possible "size"
16 * values being hardcoded into the library (i.e. in all extern functions calling
17 * / wrapping around either function). If this ever changes, (re-)insert:
19 * if (0 == size || size > 32 || 0 != size % 8)
24 static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size);
25 static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size);
28 static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size)
31 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 int16_t bitshift = size - 8;
50 for (; bitshift >= 0; bitshift = bitshift - 8)
52 if (EOF == fputc((x >> bitshift) & 0xFF, file))
62 extern uint8_t read_uint8(FILE * file, uint8_t * x)
64 /* Since read_uintX_bigendian() works on -- and zeroes -- four bytes, direct
65 * work on values of fewer bytes would corrupt immediate neighbor values.
68 uint8_t err = read_uintX_bigendian(file, &y, 8);
75 extern uint8_t read_uint16_bigendian(FILE * file, uint16_t * x)
77 /* See read_uint8() introductory code comment for rationale. */
79 uint8_t err = read_uintX_bigendian(file, &y, 16);
86 extern uint8_t read_uint32_bigendian(FILE * file, uint32_t * x)
88 return read_uintX_bigendian(file, x, 32);
93 extern uint8_t write_uint8(uint8_t x, FILE * file)
95 return write_uintX_bigendian(file, x, 8);
100 extern uint8_t write_uint16_bigendian(uint16_t x, FILE * file)
102 return write_uintX_bigendian(file, x, 16);
107 extern uint8_t write_uint32_bigendian(uint32_t x, FILE * file)
109 return write_uintX_bigendian(file, x, 32);