Add twelve-days exercise

config.json

@@ -473,6 +473,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "twelve-days",
+        "name": "Twelve Days",
+        "uuid": "3db2af89-e1ff-43b8-acb3-a0a1ce5f5dad",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "food-chain",
         "name": "Food Chain",

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

@@ -0,0 +1,6 @@
+# Hints
+
+## General
+
+- The `$t0-9` registers can be used to temporarily store values
+- The instructions specify which registers are used as input and output

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": [
+      "impl.mips"
+    ],
+    "test": [
+      "runner.mips"
+    ],
+    "example": [
+      ".meta/example.mips"
+    ]
+  },
+  "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.mips

@@ -0,0 +1,112 @@
+# | Register | Usage        | Type    | Description                   |
+# | -------- | ------------ | ------- | ----------------------------- |
+# | `$a0`    | input        | integer | start verse                   |
+# | `$a1`    | input        | integer | end verse                     |
+# | `$a2`    | input/output | address | null-terminated output string |
+# | `$a3`    | temporary    | address | null-terminated source string |
+# | `$t0`    | temporary    | byte    | character for output          |
+# | `$t3`    | temporary    | address | pointer into array            |
+# | `$t6`    | temporary    | address | ordinals array                |
+# | `$t7`    | temporary    | address | gifts                         |
+# | `$t8`    | temporary    | address | array of offsets into gifts   |
+# | `$t9`    | temporary    | address | return address                |
+
+.globl recite
+
+.data
+
+on_the: .asciiz "On the "
+day_of: .asciiz " day of Christmas my true love gave to me: "
+gifts:  .asciiz "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:  .asciiz "first"
+second: .asciiz "second"
+third:  .asciiz "third"
+fourth: .asciiz "fourth"
+fifth:  .asciiz "fifth"
+sixth:  .asciiz "sixth"
+seventh:
+        .asciiz "seventh"
+eighth: .asciiz "eighth"
+ninth:  .asciiz "ninth"
+tenth:  .asciiz "tenth"
+eleventh:
+        .asciiz "eleventh"
+twelfth:
+        .asciiz "twelfth"
+
+ordinals:
+        .word 0
+        .word first
+        .word second
+        .word third
+        .word fourth
+        .word fifth
+        .word sixth
+        .word seventh
+        .word eighth
+        .word ninth
+        .word tenth
+        .word eleventh
+        .word twelfth
+
+offsets:
+        .word 0
+        .word 235
+        .word 213
+        .word 194
+        .word 174
+        .word 157
+        .word 137
+        .word 113
+        .word 90
+        .word 69
+        .word 48
+        .word 26
+        .word 0
+
+
+.text
+
+recite:
+        sll     $a0, $a0, 2
+        sll     $a1, $a1, 2
+        la      $t6, ordinals
+        la      $t7, gifts
+        la      $t8, offsets
+        move    $t9, $ra                # Save return address
+
+loop:
+        la      $a3, on_the
+        jal     copy_string
+
+        add     $t3, $t6, $a0
+        lw      $a3, 0($t3)             # read from ordinals
+        jal     copy_string
+
+        la      $a3, day_of
+        jal     copy_string
+
+        add     $t3, $t8, $a0
+        lw      $a3, 0($t3)             # read from offsets
+        add     $a3, $t7, $a3
+        jal     copy_string
+
+end_verse:
+        add     $a0, $a0, 4
+        ble     $a0, $a1, loop
+
+        jr      $t9
+
+
+copy_string:
+                                        # copy string from source $a3 to destination $a2
+        lb      $t0, 0($a3)             # load source byte
+        sb      $t0, 0($a2)             # write byte to destination
+        addi    $a3, $a3, 1             # increment souce pointer
+        addi    $a2, $a2, 1             # increment destination pointer
+        bne     $t0, $zero, copy_string # repeat until we have reached null terminator
+
+        subi    $a2, $a2, 1             # decrement destination pointer,
+                                        # ready to append other strings
+        jr      $ra

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

@@ -0,0 +1,55 @@
+# 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/impl.mips

@@ -0,0 +1,11 @@
+# | Register | Usage        | Type    | Description                   |
+# | -------- | ------------ | ------- | ----------------------------- |
+# | `$a0`    | input        | integer | start verse                   |
+# | `$a1`    | input        | integer | end verse                     |
+# | `$a2`    | input/output | address | null-terminated output string |
+# | `$t0-9`  | temporary    | any     | for temporary storage         |
+
+.globl recite
+
+recite:
+        jr $ra