Add diamond exercise

config.json

@@ -242,6 +242,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "diamond",
+        "name": "Diamond",
+        "uuid": "a34c2fd9-268c-498f-be02-683e71b2e7e5",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "luhn",
         "name": "Luhn",

exercises/practice/diamond/.docs/instructions.md

@@ -0,0 +1,52 @@
+# Instructions
+
+The diamond kata takes as its input a letter, and outputs it in a diamond shape.
+Given a letter, it prints a diamond starting with 'A', with the supplied letter at the widest point.
+
+## Requirements
+
+- The first row contains one 'A'.
+- The last row contains one 'A'.
+- All rows, except the first and last, have exactly two identical letters.
+- All rows have as many trailing spaces as leading spaces. (This might be 0).
+- The diamond is horizontally symmetric.
+- The diamond is vertically symmetric.
+- The diamond has a square shape (width equals height).
+- The letters form a diamond shape.
+- The top half has the letters in ascending order.
+- The bottom half has the letters in descending order.
+- The four corners (containing the spaces) are triangles.
+
+## Examples
+
+In the following examples, spaces are indicated by `·` characters.
+
+Diamond for letter 'A':
+
+```text
+A
+```
+
+Diamond for letter 'C':
+
+```text
+··A··
+·B·B·
+C···C
+·B·B·
+··A··
+```
+
+Diamond for letter 'E':
+
+```text
+····A····
+···B·B···
+··C···C··
+·D·····D·
+E·······E
+·D·····D·
+··C···C··
+···B·B···
+····A····
+```

exercises/practice/diamond/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "diamond.s"
+    ],
+    "test": [
+      "diamond_test.c"
+    ],
+    "example": [
+      ".meta/example.s"
+    ]
+  },
+  "blurb": "Given a letter, print a diamond starting with 'A' with the supplied letter at the widest point.",
+  "source": "Seb Rose",
+  "source_url": "https://web.archive.org/web/20220807163751/http://claysnow.co.uk/recycling-tests-in-tdd/"
+}

exercises/practice/diamond/.meta/example.s

@@ -0,0 +1,47 @@
+.text
+.globl rows
+
+/* void rows(char *buffer, char letter); */
+rows:
+        mov     w9, #' '
+        mov     w10, #'\n'
+        mov     x14, x0
+        sub     w2, w1, #'A'            /* offset from start of the alphabet */
+        lsl     w3, w2, #1
+        add     w3, w3, #1              /* number of rows */
+        add     w4, w3, #2
+        mov     w7, w3                  /* number of rows remaining */
+
+.row:
+        mov     w8, w3                  /* number of columns remaining, excluding newline */
+
+.column:
+        strb    w9, [x14], #1           /* store ' ' byte, post-increment */
+        sub     w8, w8, #1
+        cbnz    w8, .column
+
+        strb    w10, [x14], #1          /* store '\n' byte, post-increment */
+        sub     w7, w7, #1
+        cbnz    w7, .row
+
+        strb    wzr, [x14], #-2         /* store '\0' byte, post-decrement */
+        mov     w11, #'A'
+        add     x12, x0, x2
+        mov     x13, x12
+        sub     x14, x14, x2
+        mov     x15, x14
+
+.letter:
+        strb    w11, [x12]
+        strb    w11, [x13]
+        strb    w11, [x14]
+        strb    w11, [x15]
+        add     x12, x12, x3
+        add     x13, x13, x4
+        sub     x14, x14, x4
+        sub     x15, x15, x3
+        add     w11, w11, #1
+        cmp     w11, w1
+        ble     .letter
+
+        ret

exercises/practice/diamond/.meta/tests.toml

@@ -0,0 +1,25 @@
+# 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.
+
+[202fb4cc-6a38-4883-9193-a29d5cb92076]
+description = "Degenerate case with a single 'A' row"
+
+[bd6a6d78-9302-42e9-8f60-ac1461e9abae]
+description = "Degenerate case with no row containing 3 distinct groups of spaces"
+
+[af8efb49-14ed-447f-8944-4cc59ce3fd76]
+description = "Smallest non-degenerate case with odd diamond side length"
+
+[e0c19a95-9888-4d05-86a0-fa81b9e70d1d]
+description = "Smallest non-degenerate case with even diamond side length"
+
+[82ea9aa9-4c0e-442a-b07e-40204e925944]
+description = "Largest possible diamond"

exercises/practice/diamond/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/diamond/diamond.s

@@ -0,0 +1,5 @@
+.text
+.globl rows
+
+rows:
+    ret

exercises/practice/diamond/diamond_test.c

@@ -0,0 +1,132 @@
+#include "vendor/unity.h"
+
+#define BUFFER_SIZE 3200
+
+void rows(char *buffer, char letter);
+
+void setUp(void) {
+}
+
+void tearDown(void) {
+}
+
+void test_degenerate_case_with_a_single_a_row(void) {
+    const char expected[] =
+      "A\n";
+    char buffer[BUFFER_SIZE];
+
+    rows(buffer, 'A');
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_degenerate_case_with_no_row_containing_3_distinct_groups_of_spaces(void) {
+    TEST_IGNORE();
+    const char expected[] =
+      " A \n"
+      "B B\n"
+      " A \n";
+    char buffer[BUFFER_SIZE];
+
+    rows(buffer, 'B');
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_smallest_nondegenerate_case_with_odd_diamond_side_length(void) {
+    TEST_IGNORE();
+    const char expected[] =
+      "  A  \n"
+      " B B \n"
+      "C   C\n"
+      " B B \n"
+      "  A  \n";
+    char buffer[BUFFER_SIZE];
+
+    rows(buffer, 'C');
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_smallest_nondegenerate_case_with_even_diamond_side_length(void) {
+    TEST_IGNORE();
+    const char expected[] =
+      "   A   \n"
+      "  B B  \n"
+      " C   C \n"
+      "D     D\n"
+      " C   C \n"
+      "  B B  \n"
+      "   A   \n";
+    char buffer[BUFFER_SIZE];
+
+    rows(buffer, 'D');
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_largest_possible_diamond(void) {
+    TEST_IGNORE();
+    const char expected[] =
+      "                         A                         \n"
+      "                        B B                        \n"
+      "                       C   C                       \n"
+      "                      D     D                      \n"
+      "                     E       E                     \n"
+      "                    F         F                    \n"
+      "                   G           G                   \n"
+      "                  H             H                  \n"
+      "                 I               I                 \n"
+      "                J                 J                \n"
+      "               K                   K               \n"
+      "              L                     L              \n"
+      "             M                       M             \n"
+      "            N                         N            \n"
+      "           O                           O           \n"
+      "          P                             P          \n"
+      "         Q                               Q         \n"
+      "        R                                 R        \n"
+      "       S                                   S       \n"
+      "      T                                     T      \n"
+      "     U                                       U     \n"
+      "    V                                         V    \n"
+      "   W                                           W   \n"
+      "  X                                             X  \n"
+      " Y                                               Y \n"
+      "Z                                                 Z\n"
+      " Y                                               Y \n"
+      "  X                                             X  \n"
+      "   W                                           W   \n"
+      "    V                                         V    \n"
+      "     U                                       U     \n"
+      "      T                                     T      \n"
+      "       S                                   S       \n"
+      "        R                                 R        \n"
+      "         Q                               Q         \n"
+      "          P                             P          \n"
+      "           O                           O           \n"
+      "            N                         N            \n"
+      "             M                       M             \n"
+      "              L                     L              \n"
+      "               K                   K               \n"
+      "                J                 J                \n"
+      "                 I               I                 \n"
+      "                  H             H                  \n"
+      "                   G           G                   \n"
+      "                    F         F                    \n"
+      "                     E       E                     \n"
+      "                      D     D                      \n"
+      "                       C   C                       \n"
+      "                        B B                        \n"
+      "                         A                         \n";
+    char buffer[BUFFER_SIZE];
+
+    rows(buffer, 'Z');
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+int main(void) {
+    UNITY_BEGIN();
+    RUN_TEST(test_degenerate_case_with_a_single_a_row);
+    RUN_TEST(test_degenerate_case_with_no_row_containing_3_distinct_groups_of_spaces);
+    RUN_TEST(test_smallest_nondegenerate_case_with_odd_diamond_side_length);
+    RUN_TEST(test_smallest_nondegenerate_case_with_even_diamond_side_length);
+    RUN_TEST(test_largest_possible_diamond);
+    return UNITY_END();
+}