add minimal example for algorithm

algorithms/example/Makefile.am

@@ -0,0 +1,5 @@
+noinst_LIBRARIES= libexample.a
+
+
+libexample_a_SOURCES	= plugin.c
+

algorithms/example/plugin.c

@@ -0,0 +1,67 @@
+#include <string.h>
+
+#include "miner.h"
+
+typedef struct {
+   int N;
+   double x;
+} example_param_t;
+
+static example_param_t default_param;
+
+int init_EXAMPLE() {
+    default_param.N = 1023;
+    default_param.x = 12.1;
+
+	return 0; // 0 == success
+}
+
+void* thread_init_EXAMPLE(int* error, void *extra_param) {
+    example_param_t *p = (example_param_t*) extra_param;
+
+	void *buff = malloc((size_t)p->N * 1234);
+	*error = (buff == NULL);
+	return buff;
+}
+
+
+int scanhash_EXAMPLE(int thr_id, uint32_t *pdata,
+	unsigned char *scratchbuf, const uint32_t *ptarget,
+	uint32_t max_nonce, unsigned long *hashes_done, void *extra_param) {
+
+    example_param_t *p = (example_param_t*) extra_param;
+
+	// c.f. scrypt or sha256d code for usage of other parameters
+	return 0;
+}
+
+void *param_default_EXAMPLE() {
+	return (void*) &default_param;
+}
+
+void *param_parse_EXAMPLE(const char *str, int *error) {
+    static example_param_t p;
+	const char *delim = ",";
+    char *pch = strtok (str, delim);
+    int  i = 0;
+
+    while( pch ) {
+		switch(i) {
+			case 0:
+				p.N = strtol(pch, NULL, 10);
+				applog(LOG_INFO, "example: Setting parameter N to %i", p.N);
+				break;
+			case 1:
+				p.x = strtod(pch, NULL);
+				applog(LOG_INFO, "example: Setting parameter x to %f", p.x);
+				break;
+			default:
+				applog(LOG_ERR, "Too many parameters specified to example algorithm: %s", str);
+				*error = 1;
+				return NULL;
+		}
+		i++;
+		pch = strtok (NULL, delim);
+    }
+	return (void*) &p;
+}

algorithms/example/plugin.h

@@ -0,0 +1,18 @@
+#ifndef EXAMPLE_PLUGIN_H
+#define EXAMPLE_PLUGIN_H
+
+#define PLUGIN_NAME_EXAMPLE "example"
+#define PLUGIN_DESC_EXAMPLE "example(N, x), default: N=1024, x=12.1"
+
+int init_EXAMPLE();
+void* thread_init_EXAMPLE(int* error, void *extra_param);
+
+int scanhash_EXAMPLE(int thr_id, uint32_t *pdata,
+        void *thread_local_data, const uint32_t *ptarget,
+        uint32_t max_nonce, unsigned long *hashes_done, void* extra_param);
+
+void *param_default_EXAMPLE();
+
+void *param_parse_EXAMPLE( const char *str, int *error);
+
+#endif // EXAMPLE_PLUGIN_H