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%% options
copyright owner = Dirk Krause
copyright year = 2015-xxxx
license = bsd
%% header
/** @file dk4bf.h Bit fields.
*/
#ifndef DK4ERROR_H_INCLUDED
#include "dk4error.h"
#endif
/** Bit field structure.
*/
typedef struct {
unsigned char *d; /**< Data buffer. */
size_t s; /**< Number of bits in the array. */
} dk4_bit_field_t;
#ifdef __cplusplus
extern "C" {
#endif
/** Open bit field.
@param sz Size of the bit field (number of bits).
@param erp Error report, may be NULL.
@return Pointer to new bit field on success, NULL on error.
Error codes:
- DK4_E_INVALID_ARGUMENTS<br>
if sz is 0,
- DK4_E_MEMORY_ALLOCATION_FAILED<br>
if not enough memory was available.
*/
dk4_bit_field_t *
dk4bf_open(size_t sz, dk4_er_t *erp);
/** Set one bit in a bit field.
@param dptr Bit field.
@param bitno Index of bit to modify.
@param val Bit value.
@param erp Error report, may be NULL.
@return 1 on success, 0 on error.
Error codes:
- DK4_E_INVALID_ARGUMENTS<br>
if dptr is 0 or bitno is outside the bit field size.
*/
int
dk4bf_set(dk4_bit_field_t *dptr, size_t bitno, int val, dk4_er_t *erp);
/** Retrieve one value from bit field.
@param dptr Address of result variable.
@param bfptr Bit field.
@param bitno Number of bit to obtain.
@param erp Error report, may be NULL.
@return 1 on success (dptr set), 0 on error (dptr unchanged).
Error codes:
- DK4_E_INVALID_ARGUMENTS<br>
if dptr or bfptr is NULL or bitno is outside the bit field size.
*/
int
dk4bf_get(int *dptr, dk4_bit_field_t *bfptr, size_t bitno, dk4_er_t *erp);
/** Close bit field.
@param ptr Pointer to bit field previously opened using
dk4bf_open().
*/
void
dk4bf_close(dk4_bit_field_t *ptr);
#ifdef __cplusplus
}
#endif
%% module
#include "dk4bf.h"
#include "dk4mem.h"
$!trace-include
/** Position of single bits within a byte.
*/
static const unsigned char dk4bf_bits_in_byte[] = {
0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01
};
dk4_bit_field_t *
dk4bf_open(size_t sz, dk4_er_t *erp)
{
dk4_bit_field_t *back = NULL;
size_t bsz;
if (0 < sz) {
back = dk4mem_new(dk4_bit_field_t,1,erp);
if (NULL != back) {
back->s = sz;
bsz = sz / 8;
if (0 != (sz % 8)) {
bsz++;
}
back->d = dk4mem_new(unsigned char,bsz,erp);
if (NULL == back->d) {
dk4bf_close(back);
back = NULL;
}
}
} else {
dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
}
return back;
}
int
dk4bf_set(dk4_bit_field_t *dptr, size_t bitno, int val, dk4_er_t *erp)
{
size_t bytei; /* Byte index */
size_t biti; /* Bit index */
int back = 0;
if (NULL != dptr) {
if (bitno < dptr->s) {
bytei = bitno / 8;
biti = bitno % 8;
if (0 != val) {
(dptr->d)[bytei] |= dk4bf_bits_in_byte[biti];
} else {
(dptr->d)[bytei] &= (~(dk4bf_bits_in_byte[biti]));
}
back = 1;
} else {
dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
}
} else {
dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
}
return back;
}
int
dk4bf_get(int *dptr, dk4_bit_field_t *bfptr, size_t bitno, dk4_er_t *erp)
{
size_t bytei; /* Byte index */
size_t biti; /* Bit index within byte */
int back = 0;
if ((NULL != dptr) && (NULL != bfptr)) {
if (bitno < bfptr->s) {
bytei = bitno / 8;
biti = bitno % 8;
if (0x00 != (((bfptr->d)[bytei]) & (dk4bf_bits_in_byte[biti]))) {
*dptr = 1;
} else {
*dptr = 0;
}
back = 1;
} else {
dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
}
} else {
dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
}
return back;
}
void
dk4bf_close(dk4_bit_field_t *ptr)
{
if (NULL != ptr) {
dk4mem_release(ptr->d);
dk4mem_free(ptr);
}
}
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