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);
+}