ethash_io_prepare takes seedhash as an argument

- Also typedefing a blockhash (uint8_t[32]) as an ethash_blockhash_t

io.c

@@ -60,6 +60,7 @@ bool ethash_io_write(char const *dirname,
 {
     ethash_params p;
     char info_buffer[DAG_MEMO_BYTESIZE];
+    ethash_blockhash_t seedhash;
 
 	p.cache_size = ethash_get_cachesize(block_number);
 	p.full_size = ethash_get_datasize(block_number);
@@ -74,7 +75,8 @@ bool ethash_io_write(char const *dirname,
         goto fail_free;
     }
 
-    ethash_io_serialize_info(REVISION, block_number, info_buffer);
+    ethash_get_seedhash((uint8_t*)&seedhash, block_number);
+    ethash_io_serialize_info(REVISION, seedhash, info_buffer);
     if (!ethash_io_write_file(dirname, PASS_ARR(DAG_MEMO_NAME), info_buffer, DAG_MEMO_BYTESIZE)) {
         goto fail_free;
     }

io.h

@@ -28,6 +28,8 @@
 extern "C" {
 #endif
 
+typedef struct ethash_blockhash { uint8_t b[32]; } ethash_blockhash_t;
+
 static const char DAG_FILE_NAME[] = "full";
 static const char DAG_MEMO_NAME[] = "full.info";
 static const unsigned int DAG_MEMO_BYTESIZE = 36;
@@ -47,10 +49,10 @@ enum ethash_io_rc {
  *
  * @param dirname        A null terminated c-string of the path of the ethash
  *                       data directory. If it does not exist it's created.
- * @param block_number   The current block number. Used in seedhash calculation.
+ * @param seedhash       The seedhash of the current block number
  * @return               For possible return values @see enum ethash_io_rc
  */
-enum ethash_io_rc ethash_io_prepare(char const *dirname, uint32_t block_number);
+enum ethash_io_rc ethash_io_prepare(char const *dirname, ethash_blockhash_t seedhash);
 /**
  * Fully computes data and writes it to the file on disk.
  *
@@ -80,12 +82,12 @@ bool ethash_io_write(char const *dirname,
                      size_t *data_size);
 
 static inline void ethash_io_serialize_info(uint32_t revision,
-                                            uint32_t block_number,
+                                            ethash_blockhash_t seed_hash,
                                             char *output)
 {
     // if .info is only consumed locally we don't really care about endianess
     memcpy(output, &revision, 4);
-    ethash_get_seedhash((uint8_t*)(output + 4), block_number);
+    memcpy(output + 4, &seed_hash, 32);
 }
 
 static inline char *ethash_io_create_filename(char const *dirname,

io_posix.c

@@ -27,7 +27,7 @@
 #include <stdio.h>
 #include <unistd.h>
 
-enum ethash_io_rc ethash_io_prepare(char const *dirname, uint32_t block_number)
+enum ethash_io_rc ethash_io_prepare(char const *dirname, ethash_blockhash_t seedhash)
 {
     char read_buffer[DAG_MEMO_BYTESIZE];
     char expect_buffer[DAG_MEMO_BYTESIZE];
@@ -56,7 +56,7 @@ enum ethash_io_rc ethash_io_prepare(char const *dirname, uint32_t block_number)
         goto close;
     }
 
-    ethash_io_serialize_info(REVISION, block_number, expect_buffer);
+    ethash_io_serialize_info(REVISION, seedhash, expect_buffer);
     if (memcmp(read_buffer, expect_buffer, DAG_MEMO_BYTESIZE) != 0) {
         // we have different memo contents so delete the memo file
         if (unlink(memofile) != 0) {

io_win32.c

@@ -24,7 +24,7 @@
 #include <errno.h>
 #include <stdio.h>
 
-enum ethash_io_rc ethash_io_prepare(char const *dirname, uint32_t block_number)
+enum ethash_io_rc ethash_io_prepare(char const *dirname, ethash_blockhash_t seedhash)
 {
     char read_buffer[DAG_MEMO_BYTESIZE];
     char expect_buffer[DAG_MEMO_BYTESIZE];
@@ -53,7 +53,7 @@ enum ethash_io_rc ethash_io_prepare(char const *dirname, uint32_t block_number)
         goto close;
     }
 
-    ethash_io_serialize_info(REVISION, block_number, expect_buffer);
+    ethash_io_serialize_info(REVISION, seedhash, expect_buffer);
     if (memcmp(read_buffer, expect_buffer, DAG_MEMO_BYTESIZE) != 0) {
         // we have different memo contents so delete the memo file
         if (_unlink(memofile) != 0) {