Add space-age exercise

config.json

@@ -162,6 +162,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "space-age",
+        "name": "Space Age",
+        "uuid": "24c7e0dc-6c3e-405e-8449-c8da0100545d",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "atbash-cipher",
         "name": "Atbash Cipher",

exercises/practice/space-age/.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/space-age/.docs/instructions.append.md

@@ -0,0 +1,16 @@
+# Instructions append
+
+## Output format
+
+Output the age in hundredths of a year.
+
+For example, 100 × 1,000,000,000 ÷ 31,557,600 ≈ 3,169, so someone 1,000,000,000 seconds old is `3169` hundredths of an Earth-year old.
+
+## Registers
+
+| Register | Usage     | Type    | Description                   |
+| -------- | --------- | ------- | ----------------------------- |
+| `$a0`    | input     | integer | planet (`0` = Mercury, `1` = Venus, `2` = Earth, `3` = Mars, `4` = Jupiter, `5` = Saturn, `6` = Uranus, `7` = Neptune) |
+| `$a1`    | input     | integer | seconds                       |
+| `$v0`    | output    | integer | age in hundredths of a year   |
+| `$t0-9`  | temporary | any     | used for temporary storage    |

exercises/practice/space-age/.docs/instructions.md

@@ -0,0 +1,28 @@
+# Instructions
+
+Given an age in seconds, calculate how old someone would be on a planet in our Solar System.
+
+One Earth year equals 365.25 Earth days, or 31,557,600 seconds.
+If you were told someone was 1,000,000,000 seconds old, their age would be 31.69 Earth-years.
+
+For the other planets, you have to account for their orbital period in Earth Years:
+
+| Planet  | Orbital period in Earth Years |
+| ------- | ----------------------------- |
+| Mercury | 0.2408467                     |
+| Venus   | 0.61519726                    |
+| Earth   | 1.0                           |
+| Mars    | 1.8808158                     |
+| Jupiter | 11.862615                     |
+| Saturn  | 29.447498                     |
+| Uranus  | 84.016846                     |
+| Neptune | 164.79132                     |
+
+~~~~exercism/note
+The actual length of one complete orbit of the Earth around the sun is closer to 365.256 days (1 sidereal year).
+The Gregorian calendar has, on average, 365.2425 days.
+While not entirely accurate, 365.25 is the value used in this exercise.
+See [Year on Wikipedia][year] for more ways to measure a year.
+
+[year]: https://en.wikipedia.org/wiki/Year#Summary
+~~~~

exercises/practice/space-age/.docs/introduction.md

@@ -0,0 +1,20 @@
+# Introduction
+
+The year is 2525 and you've just embarked on a journey to visit all planets in the Solar System (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune).
+The first stop is Mercury, where customs require you to fill out a form (bureaucracy is apparently _not_ Earth-specific).
+As you hand over the form to the customs officer, they scrutinize it and frown.
+"Do you _really_ expect me to believe you're just 50 years old?
+You must be closer to 200 years old!"
+
+Amused, you wait for the customs officer to start laughing, but they appear to be dead serious.
+You realize that you've entered your age in _Earth years_, but the officer expected it in _Mercury years_!
+As Mercury's orbital period around the sun is significantly shorter than Earth, you're actually a lot older in Mercury years.
+After some quick calculations, you're able to provide your age in Mercury Years.
+The customs officer smiles, satisfied, and waves you through.
+You make a mental note to pre-calculate your planet-specific age _before_ future customs checks, to avoid such mix-ups.
+
+~~~~exercism/note
+If you're wondering why Pluto didn't make the cut, go watch [this YouTube video][pluto-video].
+
+[pluto-video]: https://www.youtube.com/watch?v=Z_2gbGXzFbs
+~~~~

exercises/practice/space-age/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "impl.mips"
+    ],
+    "test": [
+      "runner.mips"
+    ],
+    "example": [
+      ".meta/example.mips"
+    ]
+  },
+  "blurb": "Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.",
+  "source": "Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial.",
+  "source_url": "https://pine.fm/LearnToProgram/?Chapter=01"
+}

exercises/practice/space-age/.meta/example.mips

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+# | Register | Usage     | Type    | Description                                |
+# | -------- | --------- | ------- | ------------------------------------------ |
+# | `$a0`    | input     | integer | planet (`0` = Mercury, `1` = Venus,        |
+# |          |           |         | `2` = Earth, `3` = Mars, `4` = Jupiter,    |
+# |          |           |         | `5` = Saturn, `6` = Uranus, `7` = Neptune) |
+# | `$a1`    | input     | integer | seconds                                    |
+# | `$v0`    | output    | integer | age in hundredths of a year                |
+# | `$t0`    | temporary | address | address of reciprocal of planet's period   |
+# | `$t1`    | temporary | integer | reciprocal of planet's period              |
+# | `$t2`    | temporary | integer | 0x8000, used to round up result            |
+
+.globl age
+
+.data
+
+# reciprocal of the number of seconds in a year, scaled up by 100 * 2**48
+reciprocals:  .word
+        3703353120, # Mercury,
+        1449844523, # Venus,
+        891940378,  # Earth,
+        474230585,  # Mars,
+        75189187,   # Jupiter,
+        30289174,   # Saturn,
+        10616209,   # Uranus,
+        5412545     # Neptune
+
+.text
+
+age:
+        la      $t0, reciprocals
+        sll     $a0, $a0, 2
+        add     $t0, $t0, $a0
+        lw      $t1, 0($t0)             # load reciprocal of the number of seconds in a year
+        multu   $t1, $a1
+        mfhi    $v0                     # scale down by 2**32 by discarding low bits
+
+        ori     $t2, $zero, 0x8000
+        addu    $v0, $v0, $t2           # scale down by 2**16, with rounding
+        srl     $v0, $v0, 16
+
+        jr      $ra

exercises/practice/space-age/.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.
+
+[84f609af-5a91-4d68-90a3-9e32d8a5cd34]
+description = "age on Earth"
+
+[ca20c4e9-6054-458c-9312-79679ffab40b]
+description = "age on Mercury"
+
+[502c6529-fd1b-41d3-8fab-65e03082b024]
+description = "age on Venus"
+
+[9ceadf5e-a0d5-4388-9d40-2c459227ceb8]
+description = "age on Mars"
+
+[42927dc3-fe5e-4f76-a5b5-f737fc19bcde]
+description = "age on Jupiter"
+
+[8469b332-7837-4ada-b27c-00ee043ebcad]
+description = "age on Saturn"
+
+[999354c1-76f8-4bb5-a672-f317b6436743]
+description = "age on Uranus"
+
+[80096d30-a0d4-4449-903e-a381178355d8]
+description = "age on Neptune"
+
+[57b96e2a-1178-40b7-b34d-f3c9c34e4bf4]
+description = "invalid planet causes error"
+include = false

exercises/practice/space-age/impl.mips

@@ -0,0 +1,22 @@
+# | Register | Usage     | Type    | Description                                |
+# | -------- | --------- | ------- | ------------------------------------------ |
+# | `$a0`    | input     | integer | planet (`0` = Mercury, `1` = Venus,        |
+# |          |           |         | `2` = Earth, `3` = Mars, `4` = Jupiter,    |
+# |          |           |         | `5` = Saturn, `6` = Uranus, `7` = Neptune) |
+# | `$a1`    | input     | integer | seconds                                    |
+# | `$v0`    | output    | integer | age in hundredths of a year                |
+# | `$t0-9`  | temporary | any     | used for temporary storage                 |
+
+.eqv MERCURY 0
+.eqv VENUS   1
+.eqv EARTH   2
+.eqv MARS    3
+.eqv JUPITER 4
+.eqv SATURN  5
+.eqv URANUS  6
+.eqv NEPTUNE 7
+
+.globl age
+
+age:
+        jr $ra

exercises/practice/space-age/runner.mips

@@ -0,0 +1,123 @@
+#
+# Test age with some examples
+#
+# s0 - num of tests left to run
+# s1 - address of planet input word
+# s2 - address of seconds input word
+# s3 - address of expected output word
+# s4 - output word
+
+.data
+# number of test cases
+n:  .word 8
+# input values (word sized ints)
+planets:  .word
+        2, # Earth,
+        0, # Mercury,
+        1, # Venus,
+        3, # Mars,
+        4, # Jupiter,
+        5, # Saturn,
+        6, # Uranus,
+        7  # Neptune
+seconds:  .word
+        1000000000,
+        2134835688,
+        189839836,
+        2129820540,
+        901876382,
+        2000000000,
+        1210792309,
+        1821023456
+# output values (word sized ints)
+outs:  .word
+        3169,
+        28088,
+        978,
+        3588,
+        241,
+        215,
+        46,
+        35
+
+failmsg: .asciiz "failed for test input: ("
+commamsg: .asciiz ", "
+expectedmsg: .asciiz "). expected "
+tobemsg: .asciiz " to be "
+okmsg: .asciiz "all tests passed"
+
+
+.text
+
+runner:
+        lw      $s0, n
+        la      $s1, planets
+        la      $s2, seconds
+        la      $s3, outs
+        j       run_test
+
+run_test:
+        lw      $a0, 0($s1)             # move input planet number to a0
+        lw      $a1, 0($s2)             # move input seconds number to a1
+        jal     age                     # call subroutine under test
+        move    $v1, $v0                # move return value in v0 to v1 because we need v0 for syscall
+
+        lw      $s4, 0($s3)             # read expected output from memory
+        bne     $v1, $s4, exit_fail     # if expected doesn't match actual, jump to fail
+
+        addi    $s1, $s1, 4             # move to next planet word in input
+        addi    $s2, $s2, 4             # move to next seconds word in input
+        addi    $s3, $s3, 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
+
+        lw      $a0, ($s1)              # print input that failed on
+        li      $v0, 1
+        syscall
+
+        la      $a0, commamsg
+        li      $v0, 4
+        syscall
+
+        lw      $a0, ($s2)
+        li      $v0, 1
+        syscall
+
+        la      $a0, expectedmsg
+        li      $v0, 4
+        syscall
+
+        move    $a0, $v1                # print actual that failed on
+        li      $v0, 1
+        syscall
+
+        la      $a0, tobemsg
+        li      $v0, 4
+        syscall
+
+        move    $a0, $s4                # print expected value that failed on
+        li      $v0, 1
+        syscall
+
+        li      $a0, 1                  # set error code to 1
+        li      $v0, 17                 # 17 is exit with error
+        syscall
+
+        jr      $ra
+
+# # Include your implementation here if you wish to run this from the MARS GUI.
+# .include "impl.mips"