diff options
Diffstat (limited to 'src/H5Tbit.c')
| -rw-r--r-- | src/H5Tbit.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/src/H5Tbit.c b/src/H5Tbit.c new file mode 100644 index 0000000..0524dcc --- /dev/null +++ b/src/H5Tbit.c @@ -0,0 +1,154 @@ +/* + * Copyright (C) 1998 NCSA + * All rights reserved. + * + * Programmer: Robb Matzke <matzke@llnl.gov> + * Wednesday, June 10, 1998 + * + * Purpose: Operations on bit vectors. A bit vector is an array of bytes + * with the least-significant bits in the first byte. That is, + * the bytes are in little-endian order. + */ +#define H5T_PACKAGE +#include <H5private.h> +#include <H5Tpkg.h> + + +/*------------------------------------------------------------------------- + * Function: H5T_bit_copy + * + * Purpose: Copies bits from one vector to another. + * + * Return: void + * + * Programmer: Robb Matzke + * Wednesday, June 10, 1998 + * + * Modifications: + * + *------------------------------------------------------------------------- + */ +void +H5T_bit_copy (uint8 *dst, size_t dst_offset, const uint8 *src, + size_t src_offset, size_t size) +{ + uintn shift; + uintn mask_lo, mask_hi; + intn s_idx, d_idx; + + /* + * Calculate shifts and masks. See diagrams below. MASK_LO in this + * example is 0x1f (the low five bits) and MASK_HI is 0xe0 (the high three + * bits). SHIFT is three since the source must be shifted right three bits + * to line up with the destination. + */ + shift = (dst_offset%8)-(src_offset%8); + mask_lo = (1<<(8-shift))-1; + mask_hi = ((1<<shift)-1) << (8-shift); + s_idx = src_offset / 8; + d_idx = dst_offset / 8; + + /* + * Get things rolling. This means copying bits until we're aligned on a + * source byte. This the following example, four bits are copied to the + * destination. + * + * src[s_idx] + * +---------------+---------------+ + * |7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0| + * +---------------+---------------+ + * ... : : : : : | | | | | + * ... v v v v v V V V V V + * ...+---------------+---------------+ + * ...|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0| + * ...+---------------+---------------+ + * dst[d_idx+1] dst[d_idx] + */ + if (src_offset%8 && size>0) { + } + + + + /* + * The middle bits. We are aligned on a source byte which needs to be + * copied to two (or one in the degenerate case) destination bytes. + * + * src[s_idx] + * +---------------+ + * |7 6 5 4 3 2 1 0| + * +---------------+ + * | | | | | | | | + * V V V V V V V V + * +---------------+---------------+ + * |7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0| + * +---------------+---------------+ + * dst[d_idx+1] dst[d_idx] + * + */ + for (/*void*/; size>8; size-=8, d_idx++, s_idx++) { + if (shift) { + dst[d_idx+0] &= mask_lo; + dst[d_idx+0] |= (src[s_idx] << shift) & mask_hi; + dst[d_idx+1] &= mask_hi; + dst[d_idx+1] |= (src[s_idx] >> (8-shift)) & mask_lo; + } else { + dst[d_idx] = src[s_idx]; + } + } + + + + + /* Finish up */ + + +} + + +/*------------------------------------------------------------------------- + * Function: H5T_bit_set + * + * Purpose: Sets or clears bits in a contiguous region of a vector + * beginning at bit OFFSET and continuing for SIZE bits. + * + * Return: void + * + * Programmer: Robb Matzke + * Wednesday, June 10, 1998 + * + * Modifications: + * + *------------------------------------------------------------------------- + */ +void +H5T_bit_set (uint8 *buf, size_t offset, size_t size, hbool_t value) +{ +} + + +/*------------------------------------------------------------------------- + * Function: H5T_bit_find + * + * Purpose: Finds the first bit with the specified VALUE within a region + * of a bit vector. The region begins at OFFSET and continues + * for SIZE bits, but the region can be searched from the least + * significat end toward the most significant end with + * + * Return: Success: The position of the bit found, relative to + * the offset. + * + * Failure: -1 + * + * Programmer: Robb Matzke + * Wednesday, June 10, 1998 + * + * Modifications: + * + *------------------------------------------------------------------------- + */ +ssize_t +H5T_bit_find (uint8 *buf, size_t offset, size_t size, H5T_sdir_t direction, + hbool_t value) +{ + return -1; +} |