Add proverb exercise

config.json

@@ -234,6 +234,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "proverb",
+        "name": "Proverb",
+        "uuid": "ce15ad3b-3423-44e9-9847-f6f73c9415e5",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "queen-attack",
         "name": "Queen Attack",

exercises/practice/proverb/.docs/instructions.md

@@ -0,0 +1,19 @@
+# Instructions
+
+For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
+
+Given a list of inputs, generate the relevant proverb.
+For example, given the list `["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]`, you will output the full text of this proverbial rhyme:
+
+```text
+For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.
+```
+
+Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content.
+No line of the output text should be a static, unchanging string; all should vary according to the input given.

exercises/practice/proverb/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "proverb.s"
+    ],
+    "test": [
+      "proverb_test.c"
+    ],
+    "example": [
+      ".meta/example.s"
+    ]
+  },
+  "blurb": "For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/For_Want_of_a_Nail"
+}

exercises/practice/proverb/.meta/example.s

@@ -0,0 +1,63 @@
+.data
+for: .string "For want of a "
+the: .string " the "
+was: .string " was lost.\n"
+and: .string "And all for the want of a ";
+end: .string ".\n";
+
+.macro APPEND str
+        adrp    x5, \str
+        add     x5, x5, :lo12:\str
+        bl      append
+.endm
+
+.text
+.globl recite
+
+append:
+        ldrb    w6, [x5], #1            /* load byte, with post-increment */
+        strb    w6, [x0], #1            /* store byte, post-increment */
+        cbnz    w6, append
+
+        sub     x0, x0, #1
+        ret
+
+/* extern void recite(char *buffer, const char **strings); */
+recite:
+        mov     x7, lr
+        mov     x2, x1
+        ldr     x3, [x2], #8            /* load, post-increment */
+        cbz     x3, .empty
+
+.next_line:
+        ldr     x4, [x2], #8            /* load, post-increment */
+        cbz     x4, .last
+
+        APPEND  for
+
+        mov     x5, x3
+        bl      append
+
+        APPEND  the
+
+        mov     x5, x4
+        bl      append
+
+        APPEND  was
+
+        mov     x3, x4
+        b       .next_line
+
+.last:
+        APPEND  and
+
+        ldr     x5, [x1]
+        bl      append
+
+        APPEND  end
+
+        mov     lr, x7
+
+.empty:
+        strb    wzr, [x0]
+        ret

exercises/practice/proverb/.meta/tests.toml

@@ -0,0 +1,28 @@
+# 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.
+
+[e974b73e-7851-484f-8d6d-92e07fe742fc]
+description = "zero pieces"
+
+[2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4]
+description = "one piece"
+
+[d9d0a8a1-d933-46e2-aa94-eecf679f4b0e]
+description = "two pieces"
+
+[c95ef757-5e94-4f0d-a6cb-d2083f5e5a83]
+description = "three pieces"
+
+[433fb91c-35a2-4d41-aeab-4de1e82b2126]
+description = "full proverb"
+
+[c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7]
+description = "four pieces modernized"

exercises/practice/proverb/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/proverb/proverb.s

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

exercises/practice/proverb/proverb_test.c

@@ -0,0 +1,129 @@
+#include "vendor/unity.h"
+
+#include <stddef.h>
+
+#define BUFFER_SIZE 400
+
+extern void recite(char *buffer, const char **strings);
+
+void setUp(void) {
+}
+
+void tearDown(void) {
+}
+
+void test_zero_pieces(void) {
+    const char *strings[] = {
+        NULL,
+    };
+    const char *expected = "";
+    char buffer[BUFFER_SIZE];
+
+    recite(buffer, strings);
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_one_piece(void) {
+    TEST_IGNORE();
+    const char *strings[] = {
+        "nail",
+        NULL,
+    };
+    const char *expected =
+        "And all for the want of a nail.\n";
+    char buffer[BUFFER_SIZE];
+
+    recite(buffer, strings);
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_two_pieces(void) {
+    TEST_IGNORE();
+    const char *strings[] = {
+        "nail",
+        "shoe",
+        NULL,
+    };
+    const char *expected =
+        "For want of a nail the shoe was lost.\n"
+        "And all for the want of a nail.\n";
+    char buffer[BUFFER_SIZE];
+
+    recite(buffer, strings);
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_three_pieces(void) {
+    TEST_IGNORE();
+    const char *strings[] = {
+        "nail",
+        "shoe",
+        "horse",
+        NULL,
+    };
+    const char *expected =
+        "For want of a nail the shoe was lost.\n"
+        "For want of a shoe the horse was lost.\n"
+        "And all for the want of a nail.\n";
+    char buffer[BUFFER_SIZE];
+
+    recite(buffer, strings);
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_full_proverb(void) {
+    TEST_IGNORE();
+    const char *strings[] = {
+        "nail",
+        "shoe",
+        "horse",
+        "rider",
+        "message",
+        "battle",
+        "kingdom",
+        NULL,
+    };
+    const char *expected =
+        "For want of a nail the shoe was lost.\n"
+        "For want of a shoe the horse was lost.\n"
+        "For want of a horse the rider was lost.\n"
+        "For want of a rider the message was lost.\n"
+        "For want of a message the battle was lost.\n"
+        "For want of a battle the kingdom was lost.\n"
+        "And all for the want of a nail.\n";
+    char buffer[BUFFER_SIZE];
+
+    recite(buffer, strings);
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+void test_four_pieces_modernized(void) {
+    TEST_IGNORE();
+    const char *strings[] = {
+        "pin",
+        "gun",
+        "soldier",
+        "battle",
+        NULL,
+    };
+    const char *expected =
+        "For want of a pin the gun was lost.\n"
+        "For want of a gun the soldier was lost.\n"
+        "For want of a soldier the battle was lost.\n"
+        "And all for the want of a pin.\n";
+    char buffer[BUFFER_SIZE];
+
+    recite(buffer, strings);
+    TEST_ASSERT_EQUAL_STRING(expected, buffer);
+}
+
+int main(void) {
+    UNITY_BEGIN();
+    RUN_TEST(test_zero_pieces);
+    RUN_TEST(test_one_piece);
+    RUN_TEST(test_two_pieces);
+    RUN_TEST(test_three_pieces);
+    RUN_TEST(test_full_proverb);
+    RUN_TEST(test_four_pieces_modernized);
+    return UNITY_END();
+}