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authorRomain Forlot <romain.forlot@iot.bzh>2017-06-20 10:24:05 +0000
committerRomain Forlot <romain.forlot@iot.bzh>2017-06-20 10:24:05 +0000
commit32e25cbca210a359b09768537b6f443fe90a3070 (patch)
tree3309794c15d8a8f8e9c1c08cad072ee1378813ba /libs/bitfield-c/src/bitfield/8byte.c
parent76c43dec62b2e21cd6446360c00d4fe6b437533f (diff)
Separation Generator to a dedicated repo
Change-Id: Id94831651c3266861435272a6e36c7884bef2c45 Signed-off-by: Romain Forlot <romain.forlot@iot.bzh>
Diffstat (limited to 'libs/bitfield-c/src/bitfield/8byte.c')
-rw-r--r--libs/bitfield-c/src/bitfield/8byte.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/libs/bitfield-c/src/bitfield/8byte.c b/libs/bitfield-c/src/bitfield/8byte.c
new file mode 100644
index 00000000..9325ed1b
--- /dev/null
+++ b/libs/bitfield-c/src/bitfield/8byte.c
@@ -0,0 +1,61 @@
+#include <bitfield/bitfield.h>
+#include <bitfield/8byte.h>
+#include <stddef.h>
+#include <limits.h>
+#include <string.h>
+
+#define EIGHTBYTE_BIT (8 * sizeof(uint64_t))
+
+uint8_t eightbyte_get_nibble(const uint64_t source, const uint8_t nibble_index,
+ const bool data_is_big_endian) {
+ return (uint8_t) eightbyte_get_bitfield(source, NIBBLE_SIZE * nibble_index,
+ NIBBLE_SIZE, data_is_big_endian);
+}
+
+uint8_t eightbyte_get_byte(uint64_t source, const uint8_t byte_index,
+ const bool data_is_big_endian) {
+ if(data_is_big_endian) {
+ source = __builtin_bswap64(source);
+ }
+ return (source >> (EIGHTBYTE_BIT - ((byte_index + 1) * CHAR_BIT))) & 0xFF;
+}
+
+// TODO is this funciton necessary anymore? is it any faster for uint64_t than
+// get_bitfield(data[], ...)? is the performance better on a 32 bit platform
+// like the PIC32?
+uint64_t eightbyte_get_bitfield(uint64_t source, const uint16_t offset,
+ const uint16_t bit_count, const bool data_is_big_endian) {
+ int startByte = offset / CHAR_BIT;
+ int endByte = (offset + bit_count - 1) / CHAR_BIT;
+
+ if(!data_is_big_endian) {
+ source = __builtin_bswap64(source);
+ }
+
+ uint8_t* bytes = (uint8_t*)&source;
+ uint64_t ret = bytes[startByte];
+ if(startByte != endByte) {
+ // The lowest byte address contains the most significant bit.
+ uint8_t i;
+ for(i = startByte + 1; i <= endByte; i++) {
+ ret = ret << 8;
+ ret = ret | bytes[i];
+ }
+ }
+
+ ret >>= 8 - find_end_bit(offset + bit_count);
+ return ret & bitmask(bit_count);
+}
+
+bool eightbyte_set_bitfield(uint64_t value, const uint16_t offset,
+ const uint16_t bit_count, uint64_t* destination) {
+ if(value > bitmask(bit_count)) {
+ return false;
+ }
+
+ int shiftDistance = EIGHTBYTE_BIT - offset - bit_count;
+ value <<= shiftDistance;
+ *destination &= ~(bitmask(bit_count) << shiftDistance);
+ *destination |= value;
+ return true;
+}