+#include "list.h"
+
+/** @file
+ * Support functions to access arbitrary bits in a byte array
+ */
+
+/**
+ * Sets @c num bits in @c _buffer, starting at the @c first bit,
+ * using the bits in @c value. This routine fast-paths writes
+ * of little-endian, byte-aligned, 32-bit words.
+ * @param _buffer The buffer whose bits will be set.
+ * @param first The bit offset in @c _buffer to start writing (0-31).
+ * @param num The number of bits from @c value to copy (1-32).
+ * @param value Up to 32 bits that will be copied to _buffer.
+ */
+static inline void buf_set_u32(void *_buffer,
+ unsigned first, unsigned num, uint32_t value)
+{
+ uint8_t *buffer = (uint8_t *)_buffer;
+
+ if ((num == 32) && (first == 0)) {
+ buffer[3] = (value >> 24) & 0xff;
+ buffer[2] = (value >> 16) & 0xff;
+ buffer[1] = (value >> 8) & 0xff;
+ buffer[0] = (value >> 0) & 0xff;
+ } else {
+ for (unsigned i = first; i < first + num; i++) {
+ if (((value >> (i - first)) & 1) == 1)
+ buffer[i / 8] |= 1 << (i % 8);
+ else
+ buffer[i / 8] &= ~(1 << (i % 8));
+ }
+ }
+}
+/**
+ * Retrieves @c num bits from @c _buffer, starting at the @c first bit,
+ * returning the bits in a 32-bit word. This routine fast-paths reads
+ * of little-endian, byte-aligned, 32-bit words.
+ * @param _buffer The buffer whose bits will be read.
+ * @param first The bit offset in @c _buffer to start reading (0-31).
+ * @param num The number of bits from @c _buffer to read (1-32).
+ * @returns Up to 32-bits that were read from @c _buffer.
+ */
+static inline uint32_t buf_get_u32(const void *_buffer,
+ unsigned first, unsigned num)
+{
+ uint8_t *buffer = (uint8_t *)_buffer;
+
+ if ((num == 32) && (first == 0)) {
+ return (((uint32_t)buffer[3]) << 24) |
+ (((uint32_t)buffer[2]) << 16) |
+ (((uint32_t)buffer[1]) << 8) |
+ (((uint32_t)buffer[0]) << 0);
+ } else {
+ uint32_t result = 0;
+ for (unsigned i = first; i < first + num; i++) {
+ if (((buffer[i / 8] >> (i % 8)) & 1) == 1)
+ result |= 1 << (i - first);
+ }
+ return result;
+ }
+}
+
+/**
+ * Inverts the ordering of bits inside a 32-bit word (e.g. 31..0 -> 0..31).
+ * This routine can be used to flip smaller data types by using smaller
+ * values for @c width.
+ * @param value The word to flip.
+ * @param width The number of bits in value (2-32).
+ * @returns A 32-bit word with @c value in reversed bit-order.
+ */
+uint32_t flip_u32(uint32_t value, unsigned width);
+
+bool buf_cmp(const void *buf1, const void *buf2, unsigned size);
+bool buf_cmp_mask(const void *buf1, const void *buf2,
+ const void *mask, unsigned size);
+
+/**
+ * Copies @c size bits out of @c from and into @c to. Any extra
+ * bits in the final byte will be set to zero.
+ * @param from The buffer to copy into @c to.
+ * @param to The buffer that will receive the copy of @c from.
+ * @param size The number of bits to copy.
+ */
+void *buf_cpy(const void *from, void *to, unsigned size);