Add grains exercise (#71)

config.json

@@ -74,6 +74,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "grains",
+        "name": "Grains",
+        "uuid": "ef1fc81b-04e5-4c59-825a-b5ca0341185d",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "square-root",
         "name": "Square Root",

exercises/practice/grains/.docs/instructions.md

@@ -0,0 +1,15 @@
+# Instructions
+
+Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
+
+There once was a wise servant who saved the life of a prince.
+The king promised to pay whatever the servant could dream up.
+Knowing that the king loved chess, the servant told the king he would like to have grains of wheat.
+One grain on the first square of a chess board, with the number of grains doubling on each successive square.
+
+There are 64 squares on a chessboard (where square 1 has one grain, square 2 has two grains, and so on).
+
+Write code that shows:
+
+- how many grains were on a given square, and
+- the total number of grains on the chessboard

exercises/practice/grains/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "grains.s"
+    ],
+    "test": [
+      "grains_test.c"
+    ],
+    "example": [
+      ".meta/example.s"
+    ]
+  },
+  "blurb": "Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.",
+  "source": "The CodeRanch Cattle Drive, Assignment 6",
+  "source_url": "https://coderanch.com/wiki/718824/Grains"
+}

exercises/practice/grains/.meta/example.s

@@ -0,0 +1,22 @@
+.text
+.globl square
+.globl total
+
+/* extern uint64_t square(int64_t number); */
+square:
+        sub     x0, x0, #1
+        cmp     x0, #64
+        bhs     .invalid                /* unsigned >= */
+
+        mov     x1, #1
+        lsl     x0, x1, x0              /* 1 << (number - 1) */
+        ret
+
+.invalid:
+        mov     x0, #0
+        ret
+
+/* extern uint64_t total(void); */
+total:
+        mov     x0, #-1                 /* all 64 bits set */
+        ret

exercises/practice/grains/.meta/tests.toml

@@ -0,0 +1,43 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[9fbde8de-36b2-49de-baf2-cd42d6f28405]
+description = "returns the number of grains on the square -> grains on square 1"
+
+[ee1f30c2-01d8-4298-b25d-c677331b5e6d]
+description = "returns the number of grains on the square -> grains on square 2"
+
+[10f45584-2fc3-4875-8ec6-666065d1163b]
+description = "returns the number of grains on the square -> grains on square 3"
+
+[a7cbe01b-36f4-4601-b053-c5f6ae055170]
+description = "returns the number of grains on the square -> grains on square 4"
+
+[c50acc89-8535-44e4-918f-b848ad2817d4]
+description = "returns the number of grains on the square -> grains on square 16"
+
+[acd81b46-c2ad-4951-b848-80d15ed5a04f]
+description = "returns the number of grains on the square -> grains on square 32"
+
+[c73b470a-5efb-4d53-9ac6-c5f6487f227b]
+description = "returns the number of grains on the square -> grains on square 64"
+
+[1d47d832-3e85-4974-9466-5bd35af484e3]
+description = "returns the number of grains on the square -> square 0 is invalid"
+
+[61974483-eeb2-465e-be54-ca5dde366453]
+description = "returns the number of grains on the square -> negative square is invalid"
+
+[a95e4374-f32c-45a7-a10d-ffec475c012f]
+description = "returns the number of grains on the square -> square greater than 64 is invalid"
+
+[6eb07385-3659-4b45-a6be-9dc474222750]
+description = "returns the total number of grains on the board"

exercises/practice/grains/Makefile

@@ -0,0 +1,36 @@
+AS = aarch64-linux-gnu-as
+CC = aarch64-linux-gnu-gcc
+
+CFLAGS = -g -Wall -Wextra -pedantic -Werror
+LDFLAGS =
+
+ALL_LDFLAGS = -pie -Wl,--fatal-warnings
+
+ALL_CFLAGS = -std=c99 -fPIE $(CFLAGS)
+ALL_LDFLAGS += $(LDFLAGS)
+
+C_OBJS = $(patsubst %.c,%.o,$(wildcard *.c))
+AS_OBJS = $(patsubst %.s,%.o,$(wildcard *.s))
+ALL_OBJS = $(filter-out example.o,$(C_OBJS) $(AS_OBJS) vendor/unity.o)
+
+CC_CMD = $(CC) $(ALL_CFLAGS) -c -o $@ $<
+
+all: tests
+	qemu-aarch64 -L /usr/aarch64-linux-gnu ./$<
+
+tests: $(ALL_OBJS)
+	@$(CC) $(ALL_CFLAGS) $(ALL_LDFLAGS) -o $@ $(ALL_OBJS)
+
+%.o: %.s
+	@$(AS) -o $@ $<
+
+%.o: %.c
+	@$(CC_CMD)
+
+vendor/unity.o: vendor/unity.c vendor/unity.h vendor/unity_internals.h
+	@$(CC_CMD)
+
+clean:
+	@rm -f *.o vendor/*.o tests
+
+.PHONY: all clean

exercises/practice/grains/grains.s

@@ -0,0 +1,9 @@
+.text
+.globl square
+.globl total
+
+square:
+    ret
+
+total:
+    ret

exercises/practice/grains/grains_test.c

@@ -0,0 +1,82 @@
+#include "vendor/unity.h"
+
+#include <stdint.h>
+
+extern uint64_t square(int64_t number);
+extern uint64_t total(void);
+
+void setUp(void) {
+}
+
+void tearDown(void) {
+}
+
+void test_grains_on_square_1(void) {
+    TEST_ASSERT_EQUAL_UINT64(1U, square(1));
+}
+
+void test_grains_on_square_2(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(2U, square(2));
+}
+
+void test_grains_on_square_3(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(4U, square(3));
+}
+
+void test_grains_on_square_4(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(8U, square(4));
+}
+
+void test_grains_on_square_16(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(32768U, square(16));
+}
+
+void test_grains_on_square_32(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(2147483648U, square(32));
+}
+
+void test_grains_on_square_64(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(9223372036854775808U, square(64));
+}
+
+void test_square_0_is_invalid(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(0U, square(0));
+}
+
+void test_negative_square_is_invalid(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(0U, square(-1));
+}
+
+void test_square_greater_than_64_is_invalid(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(0U, square(65));
+}
+
+void test_returns_the_total_number_of_grains_on_the_board(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_UINT64(18446744073709551615U, total());
+}
+
+int main(void) {
+    UNITY_BEGIN();
+    RUN_TEST(test_grains_on_square_1);
+    RUN_TEST(test_grains_on_square_2);
+    RUN_TEST(test_grains_on_square_3);
+    RUN_TEST(test_grains_on_square_4);
+    RUN_TEST(test_grains_on_square_16);
+    RUN_TEST(test_grains_on_square_32);
+    RUN_TEST(test_grains_on_square_64);
+    RUN_TEST(test_square_0_is_invalid);
+    RUN_TEST(test_negative_square_is_invalid);
+    RUN_TEST(test_square_greater_than_64_is_invalid);
+    RUN_TEST(test_returns_the_total_number_of_grains_on_the_board);
+    return UNITY_END();
+}