diff options
Diffstat (limited to 'HDF5Examples/C/H5T/h5ex_t_bitatt.c')
-rw-r--r-- | HDF5Examples/C/H5T/h5ex_t_bitatt.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/HDF5Examples/C/H5T/h5ex_t_bitatt.c b/HDF5Examples/C/H5T/h5ex_t_bitatt.c new file mode 100644 index 0000000..e4f81c3 --- /dev/null +++ b/HDF5Examples/C/H5T/h5ex_t_bitatt.c @@ -0,0 +1,147 @@ +/************************************************************ + + This example shows how to read and write bitfield + datatypes to an attribute. The program first writes bit + fields to an attribute with a dataspace of DIM0xDIM1, then + closes the file. Next, it reopens the file, reads back + the data, and outputs it to the screen. + + ************************************************************/ + +#include "hdf5.h" +#include <stdio.h> +#include <stdlib.h> + +#define FILE "h5ex_t_bitatt.h5" +#define DATASET "DS1" +#define ATTRIBUTE "A1" +#define DIM0 4 +#define DIM1 7 + +int +main(void) +{ + hid_t file, space, dset, attr; /* Handles */ + herr_t status; + hsize_t dims[2] = {DIM0, DIM1}; + unsigned char wdata[DIM0][DIM1], /* Write buffer */ + **rdata; /* Read buffer */ + int ndims, A, B, C, D; + hsize_t i, j; + + /* + * Initialize data. We will manually pack 4 2-bit integers into + * each unsigned char data element. + */ + for (i = 0; i < DIM0; i++) + for (j = 0; j < DIM1; j++) { + wdata[i][j] = 0; + wdata[i][j] |= (i * j - j) & 0x03; /* Field "A" */ + wdata[i][j] |= (i & 0x03) << 2; /* Field "B" */ + wdata[i][j] |= (j & 0x03) << 4; /* Field "C" */ + wdata[i][j] |= ((i + j) & 0x03) << 6; /* Field "D" */ + } + + /* + * Create a new file using the default properties. + */ + file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT); + + /* + * Create dataset with a null dataspace. + */ + space = H5Screate(H5S_NULL); + dset = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT); + status = H5Sclose(space); + + /* + * Create dataspace. Setting maximum size to NULL sets the maximum + * size to be the current size. + */ + space = H5Screate_simple(2, dims, NULL); + + /* + * Create the attribute and write the bitfield data to it. + */ + attr = H5Acreate(dset, ATTRIBUTE, H5T_STD_B8BE, space, H5P_DEFAULT, H5P_DEFAULT); + status = H5Awrite(attr, H5T_NATIVE_B8, wdata[0]); + + /* + * Close and release resources. + */ + status = H5Aclose(attr); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Fclose(file); + + /* + * Now we begin the read section of this example. Here we assume + * the attribute has the same name and rank, but can have any size. + * Therefore we must allocate a new array to read in data using + * malloc(). + */ + + /* + * Open file, dataset, and attribute. + */ + file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT); + dset = H5Dopen(file, DATASET, H5P_DEFAULT); + attr = H5Aopen(dset, ATTRIBUTE, H5P_DEFAULT); + + /* + * Get dataspace and allocate memory for read buffer. This is a + * two dimensional attribute so the dynamic allocation must be done + * in steps. + */ + space = H5Aget_space(attr); + ndims = H5Sget_simple_extent_dims(space, dims, NULL); + + /* + * Allocate array of pointers to rows. + */ + rdata = (unsigned char **)malloc(dims[0] * sizeof(unsigned char *)); + + /* + * Allocate space for bitfield data. + */ + rdata[0] = (unsigned char *)malloc(dims[0] * dims[1] * sizeof(unsigned char)); + + /* + * Set the rest of the pointers to rows to the correct addresses. + */ + for (i = 1; i < dims[0]; i++) + rdata[i] = rdata[0] + i * dims[1]; + + /* + * Read the data. + */ + status = H5Aread(attr, H5T_NATIVE_B8, rdata[0]); + + /* + * Output the data to the screen. + */ + printf("%s:\n", ATTRIBUTE); + for (i = 0; i < dims[0]; i++) { + printf(" ["); + for (j = 0; j < dims[1]; j++) { + A = rdata[i][j] & 0x03; /* Retrieve field "A" */ + B = (rdata[i][j] >> 2) & 0x03; /* Retrieve field "B" */ + C = (rdata[i][j] >> 4) & 0x03; /* Retrieve field "C" */ + D = (rdata[i][j] >> 6) & 0x03; /* Retrieve field "D" */ + printf(" {%d, %d, %d, %d}", A, B, C, D); + } + printf(" ]\n"); + } + + /* + * Close and release resources. + */ + free(rdata[0]); + free(rdata); + status = H5Aclose(attr); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Fclose(file); + + return 0; +} |