Made Price_t member offsets available to Rust (#203)

* added price_t member offsets to bindings.h

* Fix inconsistent naming

* Add aggregate offset

Co-authored-by: Guillermo Bescos <guibescos>

Author: majabbour

program/rust/src/bindings.h

@@ -11,4 +11,5 @@ typedef unsigned int uint32_t;
 typedef signed long int int64_t;
 typedef unsigned long int uint64_t;
 
-#include "../../c/src/oracle/oracle.h"
+#include "../../c/src/oracle/oracle.h"
+#include "price_t_offsets.h"

program/rust/src/price_t_offsets.h

@@ -0,0 +1,14 @@
+//The constants below are used by the rust oracle to efficiently access members in price_t
+//price_t is a big struct, attemting to deserialize all of it directly in borsh causes stack
+//issues on Solana. It is also more efficient to only access the members we need
+#include "../../c/src/oracle/oracle.h"
+#include <stddef.h>
+const size_t PRICE_T_EXPO_OFFSET = offsetof(struct pc_price, expo_);
+const size_t PRICE_T_TIMESTAMP_OFFSET = offsetof(struct pc_price, timestamp_);
+const size_t PRICE_T_AGGREGATE_OFFSET = offsetof(struct pc_price, agg_);
+const size_t PRICE_T_AGGREGATE_CONF_OFFSET = offsetof(struct pc_price, agg_) + offsetof(struct pc_price_info, conf_);
+const size_t PRICE_T_AGGREGATE_PRICE_OFFSET = offsetof(struct pc_price, agg_) + offsetof(struct pc_price_info, price_);
+const size_t PRICE_T_AGGREGATE_STATUS_OFFSET = offsetof(struct pc_price, agg_) + offsetof(struct pc_price_info, status_);
+const size_t PRICE_T_PREV_TIMESTAMP_OFFSET = offsetof(struct pc_price, prev_timestamp_);
+const size_t PRICE_T_PREV_CONF_OFFSET = offsetof(struct pc_price, prev_conf_);
+const size_t PRICE_T_PREV_AGGREGATE_OFFSET = offsetof(struct pc_price, prev_price_);