Add twelve-days exercise

config.json

@@ -290,6 +290,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "twelve-days",
+        "name": "Twelve Days",
+        "uuid": "5577113a-b0b0-4a72-94ae-765a52a1de45",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "all-your-base",
         "name": "All Your Base",

exercises/practice/twelve-days/.docs/instructions.md

@@ -0,0 +1,36 @@
+# Instructions
+
+Your task in this exercise is to write code that returns the lyrics of the song: "The Twelve Days of Christmas."
+
+"The Twelve Days of Christmas" is a common English Christmas carol.
+Each subsequent verse of the song builds on the previous verse.
+
+The lyrics your code returns should _exactly_ match the full song text shown below.
+
+## Lyrics
+
+```text
+On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+
+On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+```

exercises/practice/twelve-days/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "twelve_days.s"
+    ],
+    "test": [
+      "twelve_days_test.c"
+    ],
+    "example": [
+      ".meta/example.s"
+    ]
+  },
+  "blurb": "Output the lyrics to 'The Twelve Days of Christmas'.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song)"
+}

exercises/practice/twelve-days/.meta/example.s

@@ -0,0 +1,97 @@
+.data
+on:     .string "On the "
+day:    .string " day of Christmas my true love gave to me: "
+gifts:  .string "twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.\n"
+
+first:  .string "first"
+second: .string "second"
+third:  .string "third"
+fourth: .string "fourth"
+fifth:  .string "fifth"
+sixth:  .string "sixth"
+seventh:
+        .string "seventh"
+eighth: .string "eighth"
+ninth:  .string "ninth"
+tenth:  .string "tenth"
+eleventh:
+        .string "eleventh"
+twelfth:
+        .string "twelfth"
+
+ordinals:
+        .dword 0
+        .dword first
+        .dword second
+        .dword third
+        .dword fourth
+        .dword fifth
+        .dword sixth
+        .dword seventh
+        .dword eighth
+        .dword ninth
+        .dword tenth
+        .dword eleventh
+        .dword twelfth
+
+offsets:
+        .dword 0
+        .dword 235
+        .dword 213
+        .dword 194
+        .dword 174
+        .dword 157
+        .dword 137
+        .dword 113
+        .dword 90
+        .dword 69
+        .dword 48
+        .dword 26
+        .dword 0
+
+.macro LOAD register, label
+        adrp    \register, \label
+        add     \register, \register, :lo12:\label
+.endm
+
+.macro APPEND str
+
+.copy_\str:
+        ldrb    w9, [x8], #1            /* load byte, with post-increment */
+        strb    w9, [x0], #1            /* store byte, post-increment */
+        cbnz    w9, .copy_\str
+
+        sub     x0, x0, #1
+.endm
+
+.text
+.globl recite
+
+/* extern void recite(char *buffer, int start_verse, int end_verse); */
+recite:
+        LOAD    x3, on
+        LOAD    x4, day
+        LOAD    x5, gifts
+        LOAD    x6, ordinals
+        LOAD    x7, offsets
+        lsl     x1, x1, #3
+        lsl     x2, x2, #3
+
+.line:
+        mov     x8, x3
+        APPEND  on
+
+        ldr     x8, [x6, x1]
+        APPEND  ordinal
+
+        mov     x8, x4
+        APPEND  day
+
+        ldr     x8, [x7, x1]
+        add     x8, x5, x8
+        APPEND  gift
+
+        cmp     x1, x2
+        add     x1, x1, #8
+        bne     .line
+        ret

exercises/practice/twelve-days/.meta/tests.toml

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+# 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.
+
+[c0b5a5e6-c89d-49b1-a6b2-9f523bff33f7]
+description = "verse -> first day a partridge in a pear tree"
+
+[1c64508a-df3d-420a-b8e1-fe408847854a]
+description = "verse -> second day two turtle doves"
+
+[a919e09c-75b2-4e64-bb23-de4a692060a8]
+description = "verse -> third day three french hens"
+
+[9bed8631-ec60-4894-a3bb-4f0ec9fbe68d]
+description = "verse -> fourth day four calling birds"
+
+[cf1024f0-73b6-4545-be57-e9cea565289a]
+description = "verse -> fifth day five gold rings"
+
+[50bd3393-868a-4f24-a618-68df3d02ff04]
+description = "verse -> sixth day six geese-a-laying"
+
+[8f29638c-9bf1-4680-94be-e8b84e4ade83]
+description = "verse -> seventh day seven swans-a-swimming"
+
+[7038d6e1-e377-47ad-8c37-10670a05bc05]
+description = "verse -> eighth day eight maids-a-milking"
+
+[37a800a6-7a56-4352-8d72-0f51eb37cfe8]
+description = "verse -> ninth day nine ladies dancing"
+
+[10b158aa-49ff-4b2d-afc3-13af9133510d]
+description = "verse -> tenth day ten lords-a-leaping"
+
+[08d7d453-f2ba-478d-8df0-d39ea6a4f457]
+description = "verse -> eleventh day eleven pipers piping"
+
+[0620fea7-1704-4e48-b557-c05bf43967f0]
+description = "verse -> twelfth day twelve drummers drumming"
+
+[da8b9013-b1e8-49df-b6ef-ddec0219e398]
+description = "lyrics -> recites first three verses of the song"
+
+[c095af0d-3137-4653-ad32-bfb899eda24c]
+description = "lyrics -> recites three verses from the middle of the song"
+
+[20921bc9-cc52-4627-80b3-198cbbfcf9b7]
+description = "lyrics -> recites the whole song"

exercises/practice/twelve-days/Makefile

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+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/twelve-days/twelve_days.s

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