Add pangram exercise (#201)

config.json

@@ -258,6 +258,14 @@
         "difficulty": 3,
         "topics": []
       },
+      {
+        "slug": "pangram",
+        "name": "Pangram",
+        "uuid": "4a772784-2896-4c70-a2b0-71d45f302261",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "nucleotide-count",
         "name": "Nucleotide Count",

exercises/practice/pangram/.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/pangram/.docs/instructions.append.md

@@ -0,0 +1,9 @@
+# Instructions append
+
+## Registers
+
+| Register | Usage     | Type    | Description                                      |
+| -------- | --------- | ------- | ------------------------------------------------ |
+| `$a0`    | input     | address | null-terminated input string                     |
+| `$v0`    | output    | boolean | input is a pangram (`0` = `false`, `1` = `true`) |
+| `$t0-9`  | temporary | any     | used for temporary storage                       |

exercises/practice/pangram/.docs/instructions.md

@@ -0,0 +1,8 @@
+# Instructions
+
+Your task is to figure out if a sentence is a pangram.
+
+A pangram is a sentence using every letter of the alphabet at least once.
+It is case insensitive, so it doesn't matter if a letter is lower-case (e.g. `k`) or upper-case (e.g. `K`).
+
+For this exercise, a sentence is a pangram if it contains each of the 26 letters in the English alphabet.

exercises/practice/pangram/.docs/introduction.md

@@ -0,0 +1,16 @@
+# Introduction
+
+You work for a company that sells fonts through their website.
+They'd like to show a different sentence each time someone views a font on their website.
+To give a comprehensive sense of the font, the random sentences should use **all** the letters in the English alphabet.
+
+They're running a competition to get suggestions for sentences that they can use.
+You're in charge of checking the submissions to see if they are valid.
+
+~~~~exercism/note
+Pangram comes from Greek, παν γράμμα, pan gramma, which means "every letter".
+
+The best known English pangram is:
+
+> The quick brown fox jumps over the lazy dog.
+~~~~

exercises/practice/pangram/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "impl.mips"
+    ],
+    "test": [
+      "runner.mips"
+    ],
+    "example": [
+      ".meta/example.mips"
+    ]
+  },
+  "blurb": "Determine if a sentence is a pangram.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Pangram"
+}

exercises/practice/pangram/.meta/example.mips

@@ -0,0 +1,39 @@
+# Determine if the given string is an pangram, meaning that every letter appears at least once.
+#
+# Strategy: use the bits of a single word to represent set of encountered letters
+#
+# $a0 - input, pointer to null-terminated string
+# $v0 - output, boolean representing is or is not pangram
+# $t0 - set of bits
+# $t1 - 1
+# $t2 - an encountered character
+# $t3 - 'a'
+# $t4 - 'z'
+
+.globl is_pangram
+
+is_pangram:
+        move    $t0, $zero              # Reset set to 0.
+        li      $t1, 1
+        li      $t3, 'a'
+        li      $t4, 'z'
+        j       load
+
+loop:
+        ori     $t2, 32                 # downcase
+        blt     $t2, $t3, increment     # If less than 'a', continue to next letter.
+        bgt     $t2, $t4, increment     # If greater than 'z', continue to next letter.
+        sub     $t2, $t2, $t3           # Calculate letter's position in alphabet.
+        sllv    $t2, $t1, $t2           # Create bit mask
+        or      $t0, $t0, $t2           # Apply to set.
+
+increment:
+        addi    $a0, $a0, 1             # Finally, increment the pointer
+
+load:
+        lb      $t2, 0($a0)             # Load a character,
+        bne     $t2, $zero, loop        # if not end of string, continue.
+
+        li      $t2, 0x3ffffff          # (2 ** 26) - 1
+        seq     $v0, $t0, $t2           # Does $t0 have all 26 letter bits set?
+        jr      $ra

exercises/practice/pangram/.meta/tests.toml

@@ -0,0 +1,45 @@
+# 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.
+
+[64f61791-508e-4f5c-83ab-05de042b0149]
+description = "empty sentence"
+
+[74858f80-4a4d-478b-8a5e-c6477e4e4e84]
+description = "perfect lower case"
+
+[61288860-35ca-4abe-ba08-f5df76ecbdcd]
+description = "only lower case"
+
+[6564267d-8ac5-4d29-baf2-e7d2e304a743]
+description = "missing the letter 'x'"
+
+[c79af1be-d715-4cdb-a5f2-b2fa3e7e0de0]
+description = "missing the letter 'h'"
+
+[d835ec38-bc8f-48e4-9e36-eb232427b1df]
+description = "with underscores"
+
+[8cc1e080-a178-4494-b4b3-06982c9be2a8]
+description = "with numbers"
+
+[bed96b1c-ff95-45b8-9731-fdbdcb6ede9a]
+description = "missing letters replaced by numbers"
+
+[938bd5d8-ade5-40e2-a2d9-55a338a01030]
+description = "mixed case and punctuation"
+
+[2577bf54-83c8-402d-a64b-a2c0f7bb213a]
+description = "case insensitive"
+include = false
+
+[7138e389-83e4-4c6e-8413-1e40a0076951]
+description = "a-m and A-M are 26 different characters but not a pangram"
+reimplements = "2577bf54-83c8-402d-a64b-a2c0f7bb213a"

exercises/practice/pangram/impl.mips

@@ -0,0 +1,10 @@
+# | Register | Usage     | Type    | Description                                      |
+# | -------- | --------- | ------- | ------------------------------------------------ |
+# | `$a0`    | input     | address | null-terminated input string                     |
+# | `$v0`    | output    | boolean | input is a pangram (`0` = `false`, `1` = `true`) |
+# | `$t0-9`  | temporary | any     | used for temporary storage                       |
+
+.globl is_pangram
+
+is_pangram:
+        jr $ra

exercises/practice/pangram/runner.mips

@@ -0,0 +1,107 @@
+#
+# Test is_pangram with some examples
+#
+# s0 - num of tests left to run
+# s1 - address of input string
+# s2 - address of expected output word
+# s3 - char byte
+# s4 - expected output word
+
+.data
+
+# number of test cases
+n:  .word 10
+# input values (null terminated)
+ins:  .asciiz
+        "",
+        "abcdefghijklmnopqrstuvwxyz",
+        "the quick brown fox jumps over the lazy dog",
+        "a quick movement of the enemy will jeopardize five gunboats",
+        "five boxing wizards jump quickly at it",
+        "the_quick_brown_fox_jumps_over_the_lazy_dog",
+        "the 1 quick brown fox jumps over the 2 lazy dogs",
+        "7h3 qu1ck brown fox jumps ov3r 7h3 lazy dog",
+        "\"Five quacking Zephyrs jolt my wax bed.\"",
+        "abcdefghijklm ABCDEFGHIJKLM"
+# expected output values (word sized ints)
+outs:  .word
+        0,
+        1,
+        1,
+        0,
+        0,
+        1,
+        1,
+        0,
+        1,
+        0
+
+failmsg: .asciiz "failed for test input: "
+expectedmsg: .asciiz ". expected "
+tobemsg: .asciiz " to be "
+okmsg: .asciiz "all tests passed"
+
+
+.text
+
+runner:
+        lw      $s0, n
+        la      $s1, ins
+        la      $s2, outs
+
+run_test:
+        move    $a0, $s1                # move address of input str to a0
+        jal     is_pangram              # call subroutine under test
+        move    $v1, $v0                # move return value in v0 to v1 because we need v0 for syscall
+
+        lw      $s4, 0($s2)             # read expected output from memory
+        bne     $v1, $s4, exit_fail     # if expected doesn't match actual, jump to fail
+
+scan:
+        lb      $s3, 0($s1)             # load byte
+        addi    $s1, $s1, 1             # move input address on byte forward
+        bne     $s3, $zero, scan        # if char not null, continue loop
+
+        addi    $s2, $s2, 4             # move to next word in output
+        sub     $s0, $s0, 1             # decrement num of tests left to run
+        bgt     $s0, $zero, run_test    # if more than zero tests to run, jump to run_test
+
+exit_ok:
+        la      $a0, okmsg              # put address of okmsg into a0
+        li      $v0, 4                  # 4 is print string
+        syscall
+
+        li      $v0, 10                 # 10 is exit with zero status (clean exit)
+        syscall
+
+exit_fail:
+        la      $a0, failmsg            # put address of failmsg into a0
+        li      $v0, 4                  # 4 is print string
+        syscall
+
+        move    $a0, $s1                # print input that failed on
+        li      $v0, 4
+        syscall
+
+        la      $a0, expectedmsg
+        li      $v0, 4
+        syscall
+
+        move    $a0, $v1                # print actual that failed on
+        li      $v0, 1                  # 1 is print integer
+        syscall
+
+        la      $a0, tobemsg
+        li      $v0, 4
+        syscall
+
+        move    $a0, $s4                # print expected value that failed on
+        li      $v0, 1                  # 1 is print integer
+        syscall
+
+        li      $a0, 1                  # set error code to 1
+        li      $v0, 17                 # 17 is exit with error
+        syscall
+
+# # Include your implementation here if you wish to run this from the MARS GUI.
+# .include "impl.mips"