Add resistor-color exercise

Adapted from x86-64-assembly.

config.json

@@ -170,6 +170,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "resistor-color",
+        "name": "Resistor Color",
+        "uuid": "89cdbbb0-1944-4f73-ac1f-7967ac55c100",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "scrabble-score",
         "name": "Scrabble Score",

exercises/practice/resistor-color/.docs/instructions.md

@@ -0,0 +1,39 @@
+# Instructions
+
+If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
+For this exercise, you need to know two things about them:
+
+- Each resistor has a resistance value.
+- Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.
+
+To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values.
+Each band has a position and a numeric value.
+
+The first 2 bands of a resistor have a simple encoding scheme: each color maps to a single number.
+
+In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands.
+
+These colors are encoded as follows:
+
+- black: 0
+- brown: 1
+- red: 2
+- orange: 3
+- yellow: 4
+- green: 5
+- blue: 6
+- violet: 7
+- grey: 8
+- white: 9
+
+The goal of this exercise is to create a way:
+
+- to look up the numerical value associated with a particular color band
+- to list the different band colors
+
+Mnemonics map the colors to the numbers, that, when stored as an array, happen to map to their index in the array:
+Better Be Right Or Your Great Big Values Go Wrong.
+
+More information on the color encoding of resistors can be found in the [Electronic color code Wikipedia article][e-color-code].
+
+[e-color-code]: https://en.wikipedia.org/wiki/Electronic_color_code

exercises/practice/resistor-color/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "resistor_color.s"
+    ],
+    "test": [
+      "resistor_color_test.c"
+    ],
+    "example": [
+      ".meta/example.s"
+    ]
+  },
+  "blurb": "Convert a resistor band's color to its numeric representation.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1458"
+}

exercises/practice/resistor-color/.meta/example.s

@@ -0,0 +1,62 @@
+.data
+black:  .string "black"
+brown:  .string "brown"
+red:    .string "red"
+orange: .string "orange"
+yellow: .string "yellow"
+green:  .string "green"
+blue:   .string "blue"
+violet: .string "violet"
+grey:   .string "grey"
+white:  .string "white"
+
+color_array:
+        .dword black
+        .dword brown
+        .dword red
+        .dword orange
+        .dword yellow
+        .dword green
+        .dword blue
+        .dword violet
+        .dword grey
+        .dword white
+        .dword 0                        /* Sentinel value to indicate end of array */
+
+.text
+.globl color_code
+.globl colors
+
+/* extern int color_code(const char *color); */
+color_code:
+        adrp    x1, color_array
+        add     x1, x1, :lo12:color_array
+        mov     x2, x1
+
+.next:
+        mov     x3, x0
+        ldr     x4, [x2], #8            /* load pointer, post-increment */
+        cbz     x4, .invalid
+
+.compare:
+        ldrb    w5, [x3], #1            /* load character, post-increment */
+        ldrb    w6, [x4], #1            /* load character, post-increment */
+        cmp     w5, w6
+        bne     .next
+
+        cbnz    w5, .compare
+
+        sub     x2, x2, #8
+        sub     x0, x2, x1
+        lsr     x0, x0, #3
+        ret
+
+.invalid:
+        mov     x0, #-1
+        ret
+
+/* extern const char **colors(void); */
+colors:
+        adrp    x0, color_array
+        add     x0, x0, :lo12:color_array
+        ret

exercises/practice/resistor-color/.meta/tests.toml

@@ -0,0 +1,22 @@
+# 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.
+
+[49eb31c5-10a8-4180-9f7f-fea632ab87ef]
+description = "Color codes -> Black"
+
+[0a4df94b-92da-4579-a907-65040ce0b3fc]
+description = "Color codes -> White"
+
+[5f81608d-f36f-4190-8084-f45116b6f380]
+description = "Color codes -> Orange"
+
+[581d68fa-f968-4be2-9f9d-880f2fb73cf7]
+description = "Colors"

exercises/practice/resistor-color/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/resistor-color/resistor_color.s

@@ -0,0 +1,9 @@
+.text
+.globl color_code
+.globl colors
+
+color_code:
+    ret
+
+colors:
+    ret

exercises/practice/resistor-color/resistor_color_test.c

@@ -0,0 +1,49 @@
+#include "vendor/unity.h"
+
+#include <stddef.h>
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+extern int color_code(const char *color);
+extern const char **colors(void);
+
+void setUp(void) {
+}
+
+void tearDown(void) {
+}
+
+void test_black(void) {
+    TEST_ASSERT_EQUAL_INT(0, color_code("black"));
+}
+
+void test_white(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(9, color_code("white"));
+}
+
+void test_orange(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(3, color_code("orange"));
+}
+
+void test_colors(void) {
+    TEST_IGNORE();
+    const char *expected[] = {"black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white"};
+    const char **color_array = colors();
+    size_t size;
+
+    for (size = 0; color_array[size]; size++) {
+    }
+    TEST_ASSERT_EQUAL_UINT(ARRAY_SIZE(expected), size);
+    TEST_ASSERT_EQUAL_STRING_ARRAY(expected, color_array, size);
+}
+
+int main(void) {
+    UNITY_BEGIN();
+    RUN_TEST(test_black);
+    RUN_TEST(test_white);
+    RUN_TEST(test_orange);
+    RUN_TEST(test_colors);
+    return UNITY_END();
+}