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-rw-r--r--libs/bitfield-c/src/bitfield/bitfield.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/libs/bitfield-c/src/bitfield/bitfield.c b/libs/bitfield-c/src/bitfield/bitfield.c
new file mode 100644
index 0000000..795f020
--- /dev/null
+++ b/libs/bitfield-c/src/bitfield/bitfield.c
@@ -0,0 +1,74 @@
+#include <bitfield/bitfield.h>
+#include <limits.h>
+#include <string.h>
+#include <stddef.h>
+#include <sys/param.h>
+
+uint64_t bitmask(const uint8_t bit_count) {
+ return (((uint64_t)0x1) << bit_count) - 1;
+}
+
+uint8_t get_nibble(const uint8_t source[], const uint8_t source_length,
+ const uint8_t nibble_index) {
+ uint8_t byte_index = nibble_index / 2;
+ uint8_t result = get_byte(source, source_length, byte_index);
+ if(nibble_index % 2 == 0) {
+ result >>= NIBBLE_SIZE;
+ }
+ result &= bitmask(NIBBLE_SIZE);
+ return result;
+}
+
+uint8_t get_byte(const uint8_t source[], const uint8_t source_length,
+ const uint8_t byte_index) {
+ if(byte_index < source_length) {
+ return source[byte_index];
+ }
+ return 0;
+}
+
+uint64_t get_bitfield(const uint8_t source[], const uint8_t source_length,
+ const uint16_t offset, const uint16_t bit_count) {
+ if(bit_count > 64 || bit_count < 1) {
+ // TODO error reporting?
+ return 0;
+ }
+
+ ArrayOrBytes combined;
+ memset(combined.bytes, 0, sizeof(combined.bytes));
+ if(copy_bits_right_aligned(source, source_length, offset, bit_count,
+ combined.bytes, sizeof(combined.bytes))) {
+ if(BYTE_ORDER == LITTLE_ENDIAN) {
+ combined.whole = __builtin_bswap64(combined.whole);
+ }
+ } else {
+ // debug("couldn't copy enough bits from source")
+ }
+ return combined.whole;
+}
+
+bool set_nibble(const uint16_t nibble_index, const uint8_t value,
+ uint8_t* destination, const uint16_t destination_length) {
+ return copy_bits(&value, CHAR_BIT, NIBBLE_SIZE, NIBBLE_SIZE, destination,
+ destination_length, nibble_index * NIBBLE_SIZE);
+}
+
+bool set_bitfield(const uint64_t value, const uint16_t offset,
+ const uint16_t bit_count, uint8_t destination[],
+ uint16_t destination_length) {
+ if(value > bitmask(bit_count)) {
+ return false;
+ }
+
+ ArrayOrBytes combined = {
+ whole: value
+ };
+
+ if(BYTE_ORDER == LITTLE_ENDIAN) {
+ combined.whole = __builtin_bswap64(combined.whole);
+ }
+
+ return copy_bits(combined.bytes, sizeof(combined.bytes),
+ sizeof(combined.bytes) * CHAR_BIT - bit_count, bit_count,
+ destination, destination_length, offset);
+}