From cdc29336f7f00fa8c7e4cf4596cb724d46ab2668 Mon Sep 17 00:00:00 2001
From: Tanguy Pruvot <tanguy.pruvot@gmail.com>
Date: Tue, 30 Sep 2014 09:37:11 +0200
Subject: [PATCH] stats: compute work difficulty from target

---
 cpu-miner.c | 30 +++++++++++++++++++++++++++---
 miner.h     | 26 ++++++++++++++++++++++++++
 util.c      |  2 +-
 3 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/cpu-miner.c b/cpu-miner.c
index cc63e30..23196a1 100644
--- a/cpu-miner.c
+++ b/cpu-miner.c
@@ -370,6 +370,8 @@ struct work {
 		uint64_t u64[1];
 	} noncerange;
 
+	double difficulty;
+
 	uint32_t scanned_from;
 	uint32_t scanned_to;
 };
@@ -450,6 +452,27 @@ err_out:
 	return false;
 }
 
+/**
+ * Calculate the work difficulty as double
+ */
+static void calc_diff(struct work *work, int known)
+{
+	// sample for diff 32.53 : 00000007de5f0000
+	const uint64_t diffone = 0xFFFF000000000000ull;
+	uint64_t *data64, d64;
+	char rtarget[32];
+
+	swab256(rtarget, work->target);
+	data64 = (uint64_t *)(rtarget + 3); /* todo: index (3) can be tuned here */
+	d64 = swab64(*data64);
+	if (unlikely(!d64))
+		d64 = 1;
+	work->difficulty = (double)diffone / d64;
+	if (opt_difficulty > 0.) {
+		work->difficulty /= opt_difficulty;
+	}
+}
+
 static int share_result(int result, const char *reason)
 {
 	char s[345];
@@ -502,6 +525,7 @@ static bool submit_upstream_work(CURL *curl, struct work *work)
 			applog(LOG_DEBUG, "DEBUG: stale work detected, discarding");
 		return true;
 	}
+	calc_diff(work, 0);
 	pthread_mutex_unlock(&g_work_lock);
 
 	if (have_stratum) {
@@ -1000,13 +1024,13 @@ static void *miner_thread(void *userdata)
 		}
 
 		if (memcmp(work.target, g_work.target, sizeof(work.target))) {
+			calc_diff(&g_work, 0);
 			if (opt_debug) {
 				uint64_t target64 = g_work.target[7] * 0x100000000ULL + g_work.target[6];
-				applog(LOG_DEBUG, "job %s target change: %llx", g_work.job_id, target64);
-				applog_hash((uint8_t*) work.target);
-				applog_compare_hash((uint8_t*) g_work.target, (uint8_t*) work.target);
+				applog(LOG_DEBUG, "job %s target change: %llx (%.1f)", g_work.job_id, target64, g_work.difficulty);
 			}
 			memcpy(work.target, g_work.target, sizeof(work.target));
+			work.difficulty = g_work.difficulty;
 			(*nonceptr) = (0xffffffffUL / opt_n_threads) * thr_id; // 0 if single thr
 			/* on new target, ignoring nonce, clear sent data (hashlog) */
 			if (memcmp(work.target, g_work.target, sizeof(work.target))) {
diff --git a/miner.h b/miner.h
index 664972b..62cff79 100644
--- a/miner.h
+++ b/miner.h
@@ -85,6 +85,8 @@ enum {
 #else
 #define bswap_32(x) ((((x) << 24) & 0xff000000u) | (((x) << 8) & 0x00ff0000u) \
                    | (((x) >> 8) & 0x0000ff00u) | (((x) >> 24) & 0x000000ffu))
+#define bswap_64(x) (((uint64_t) bswap_32((uint32_t)((x) & 0xffffffffu)) << 32) \
+                   | (uint64_t) bswap_32((uint32_t)((x) >> 32)))
 #endif
 
 static inline uint32_t swab32(uint32_t v)
@@ -96,6 +98,30 @@ static inline uint32_t swab32(uint32_t v)
 #endif
 }
 
+static inline uint64_t swab64(uint64_t v)
+{
+#ifdef WANT_BUILTIN_BSWAP
+	return __builtin_bswap64(v);
+#else
+	return bswap_64(v);
+#endif
+}
+
+static inline void swab256(void *dest_p, const void *src_p)
+{
+	uint32_t *dest = (uint32_t *) dest_p;
+	const uint32_t *src = (const uint32_t *) src_p;
+
+	dest[0] = swab32(src[7]);
+	dest[1] = swab32(src[6]);
+	dest[2] = swab32(src[5]);
+	dest[3] = swab32(src[4]);
+	dest[4] = swab32(src[3]);
+	dest[5] = swab32(src[2]);
+	dest[6] = swab32(src[1]);
+	dest[7] = swab32(src[0]);
+}
+
 #ifdef HAVE_SYS_ENDIAN_H
 #include <sys/endian.h>
 #endif
diff --git a/util.c b/util.c
index b7c7d37..4586ddd 100644
--- a/util.c
+++ b/util.c
@@ -388,7 +388,7 @@ json_t *json_rpc_call(CURL *curl, const char *url,
 	upload_data.len = strlen(rpc_req);
 	upload_data.pos = 0;
 	sprintf(len_hdr, "Content-Length: %lu", (unsigned long) upload_data.len);
-	sprintf(hashrate_hdr, "X-Mining-Hashrate: %llu", global_hashrate);
+	sprintf(hashrate_hdr, "X-Mining-Hashrate: %llu", (unsigned long long) global_hashrate);
 
 	headers = curl_slist_append(headers, "Content-Type: application/json");
 	headers = curl_slist_append(headers, len_hdr);