#include <string.h>
#include <assert.h>
-#define INDEX_BITS ((sizeof(shachain_index_t)) * CHAR_BIT)
-
static void change_bit(unsigned char *arr, size_t index)
{
arr[index / CHAR_BIT] ^= (1 << (index % CHAR_BIT));
}
-static unsigned int count_trailing_zeroes(shachain_index_t index)
+static unsigned int count_trailing_zeroes(uint64_t index)
{
#if HAVE_BUILTIN_CTZLL
- return index ? (unsigned int)__builtin_ctzll(index) : INDEX_BITS;
+ return index ? (unsigned int)__builtin_ctzll(index) : SHACHAIN_BITS;
#else
unsigned int i;
- for (i = 0; i < INDEX_BITS; i++) {
+ for (i = 0; i < SHACHAIN_BITS; i++) {
if (index & (1ULL << i))
break;
}
#endif
}
-static bool can_derive(shachain_index_t from, shachain_index_t to)
+static bool can_derive(uint64_t from, uint64_t to)
{
- shachain_index_t mask;
+ uint64_t mask;
/* Corner case: can always derive from seed. */
if (from == 0)
return true;
/* Leading bits must be the same */
- mask = ~((1ULL << count_trailing_zeroes(from))-1);
+ mask = ~(((uint64_t)1 << count_trailing_zeroes(from))-1);
return ((from ^ to) & mask) == 0;
}
-static void derive(shachain_index_t from, shachain_index_t to,
+static void derive(uint64_t from, uint64_t to,
const struct sha256 *from_hash,
struct sha256 *hash)
{
- shachain_index_t branches;
+ uint64_t branches;
int i;
assert(can_derive(from, to));
}
}
-void shachain_from_seed(const struct sha256 *seed, shachain_index_t index,
+void shachain_from_seed(const struct sha256 *seed, uint64_t index,
struct sha256 *hash)
{
derive(0, index, seed, hash);
}
+uint64_t shachain_next_index(const struct shachain *chain)
+{
+ return chain->min_index - 1;
+}
+
void shachain_init(struct shachain *chain)
{
chain->num_valid = 0;
- chain->min_index = 0;
+ /* This is 0 in the case where SHACHAIN_BITS is 64. */
+ chain->min_index = (UINT64_MAX >> (64 - SHACHAIN_BITS)) + 1;
}
bool shachain_add_hash(struct shachain *chain,
- shachain_index_t index, const struct sha256 *hash)
+ uint64_t index, const struct sha256 *hash)
{
unsigned int i, pos;
/* You have to insert them in order! */
- assert(index == chain->min_index - 1 ||
- (index == (shachain_index_t)(-1ULL) && chain->num_valid == 0));
+ assert(index == shachain_next_index(chain));
pos = count_trailing_zeroes(index);
}
bool shachain_get_hash(const struct shachain *chain,
- shachain_index_t index, struct sha256 *hash)
+ uint64_t index, struct sha256 *hash)
{
unsigned int i;