initial commit

c/grains/src/grains.c

@@ -0,0 +1,45 @@
+#include "grains.h"
+/* See GNUmakefile in following link for explanation
+ * https://exercism.io/my/solutions/103b2f7d92db42309c1988030f5202c7
+ */
+#if defined UNIT_TEST || defined DEBUG
+#include <stdio.h>
+#include <stdlib.h>
+#endif
+
+uint64_t square(uint8_t index)
+{
+    return  index>0 && index <65 ? (uint64_t)1<<(index-1): 0;
+}
+uint64_t total(void)
+{
+    /* Geometric series sum formula for 64 terms, ratio 2 and first term 1:
+     * S = 2⁰ + 2¹ + 2² + ... + 2⁶³
+     *   = (1-2⁶⁴) / (1-2)
+     *   = 2⁶⁴ - 1
+     *   = 0 - 1 for uint64_t
+     * We should write (2<<64)-1, but gcc won't compile, due to:
+     *   -Werror=shift-count-overflow
+     * Then we could avoid it by using:
+     *    #pragma GCC diagnostic ignored "-Wshift-count-overflow"
+     * but i think it is out of scope for this exercise (we should also take
+     * care of other compilers).
+     */
+    return (uint64_t) -1;
+}
+
+
+
+#ifdef UNIT_TEST
+int main(int ac, char **av)
+{
+    int arg=1;
+    uint64_t i;
+
+    for (; arg<ac; ++arg) {
+        i=atol(av[arg]);
+        printf("value(%lu)=%lu\n", i, square(i));
+    }
+    printf("total()=%lu\n", total());
+}
+#endif

c/grains/src/grains.h

@@ -0,0 +1,17 @@
+#ifndef GRAINS_H
+#define GRAINS_H
+
+#include <stdint.h>
+
+extern uint64_t square(uint8_t index);
+extern uint64_t total(void);
+
+/* See GNUmakefile in following link for explanation
+ * https://exercism.io/my/solutions/103b2f7d92db42309c1988030f5202c7
+ */
+#ifdef  TESTALL
+#undef  TEST_IGNORE
+#define TEST_IGNORE() {}
+#endif
+
+#endif