scramble

commit 494938cbb26671847308977bd20e7694cd313607
Author: Nihal Jere <noocsharp@gmail.com>
Date:   Wed, 29 Jan 2020 22:48:19 -0600

initial commit

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
16
++++++++++++++++
A
README
 | 
5
+++++
A
main.c
 | 
87
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

4 files changed, 109 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+scramble
diff --git a/Makefile b/Makefile
@@ -0,0 +1,16 @@
+PREFIX = /usr/local
+CC = cc
+
+all:
+	${CC} main.c -o scramble
+
+clean:
+	rm -f scramble
+
+install: all
+	mkdir -p ${PREFIX}/bin
+	cp -f scramble ${PREFIX}/bin
+	chmod 755 ${PREFIX}/bin/scramble
+
+uninstall:
+	rm -f ${PREFIX}/bin/scramble
diff --git a/README b/README
@@ -0,0 +1,5 @@
+# Scramble
+
+A very simple CLI 3x3 Rubik's cube scrambler - because the only other one I could find was written in Javascript.
+
+This one just checks for typographical repetitions rather than checking if the same state appeared previously in the scramble. I might add it later though.
diff --git a/main.c b/main.c
@@ -0,0 +1,87 @@
+#include <stdlib.h>
+#include <time.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <sys/random.h>
+
+#define DEFAULT_LENGTH 25
+
+static const char* pmoves[3][6] = { {"U", "D", "L", "R", "F", "B"}, {"U'", "D'", "L'", "R'", "F'", "B'"}, {"U2", "D2", "L2", "R2", "F2", "B2"} };
+
+const char help[] = "usage: scramble [LENGTH]";
+
+static char const** typo_scramble(uint8_t length) {
+    char const** moves = calloc(length, sizeof(char*));
+
+    if (moves == NULL) return NULL;
+
+    uint8_t last_side = 0;
+
+    uint8_t counter = 0;
+    // TODO deal with RAND_MAX
+    while (counter < length) {
+        uint8_t rval = (uint8_t) rand();
+        // 3 possible values for set, so 2 bits
+        uint8_t set = rval & 3;
+        // 6 possible values for side, so 3 bits
+        uint8_t side = (rval >> 2) & 7;
+
+        // prevent biasing of results that would occur if
+        // we just took the modulus of the values
+        if (set == 3 || side > 5) continue;
+
+        // if the side is the same as before, choose another side
+        if (counter != 0 && side == last_side) continue;
+
+        moves[counter++] = pmoves[set][side];
+        last_side = side;
+    }
+
+    return moves;
+}
+
+int main(int argc, char** argv) {
+    uint8_t length = DEFAULT_LENGTH;
+
+    if (argc > 2) {
+        printf("%s: Too many arguments", argv[0]);
+    } else if (argc == 2) {
+        if (argv[1] == "-h" || argv[1] == "--help") {
+            printf("%s\n", help);
+            return 0;
+        }
+
+        char* endptr = NULL;
+        long int newlength = strtol(argv[1], &endptr, 10);
+
+        if (*endptr != '\0') {
+            printf("%s: invalid length\n", argv[0]);
+            return -1;
+        }
+
+        if (0 > newlength || newlength > 255) {
+            printf("%s: invalid length, max of 255\n", argv[0]);
+            return -2;
+        }
+
+        length = newlength;
+    }
+
+    uint32_t seed = 0;
+    getrandom((void*) &seed, 4, GRND_NONBLOCK);
+    srand(seed);
+
+    const char** moves;
+
+    
+    if ((moves = typo_scramble(length)) != NULL) {
+        for (uint8_t i = 0; i < length; ++i) {
+            printf("%s ", moves[i]);
+        }
+        printf("\n");
+        free(moves);
+    }
+
+    return 0;
+
+}