bin: improve the style and add more documentation

And also run rubocop on the CI for good measure.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

5 files changed, 43 insertions, 18 deletions

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b81bc3e..4de3241 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -16,7 +16,17 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install dependencies from Ubuntu sources
-        run: sudo apt-get install cc65 ruby
+        run: sudo apt-get install cc65
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 'ruby'
+
+      - name: Lint scripts on bin/
+        run: |
+            gem install rubocop
+            rubocop bin/ --format github
 
       - name: Main task
         run: V=1 make all
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..f4a1205
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,3 @@
+AllCops:
+  SuggestExtensions: false
+  NewCops: enable
diff --git a/bin/rand.rb b/bin/rand.rb
index f627748..b781b6e 100644
--- a/bin/rand.rb
+++ b/bin/rand.rb
@@ -1,5 +1,15 @@
 # frozen_string_literal: true
 
+##
+# Generate a table of 256 bytes of pseudo-random values. These values are
+# constrained with the upper and lower margins of the screen where enemies can
+# appear, and discard certain positions like platforms that can be troublesome
+# on enemy creation. All in all not exactly super pure randomness, but on the
+# other hand this game just needs a bit of randomness.
+#
+# Whenever you update values on background.s, you are supposed to call this
+# script again and replace the values on 'valid_y_rand_table' in prng.s.
+
 # See values on background.s
 UPPER_MARGIN_Y_COORD = 0x1A
 GROUND_Y_COORD = 0xC8 - 32 # NOTE: As in background.s - twice the size of the enemy.
@@ -10,7 +20,7 @@ available = (UPPER_MARGIN_Y_COORD..GROUND_Y_COORD).to_a - (0x58..0x69).to_a - (0
 
 # With this produce the array containing a randomized sample from the
 # 'available' values.
-random_byte_array = Array.new(256) { '$%02X' % available.sample }
+random_byte_array = Array.new(256) { format('$%02X', available.sample) }
 
 # And now print it in the assembler format.
 random_byte_array.each_slice(16) do |row|
diff --git a/bin/values.rb b/bin/values.rb
index 3ff1578..e5128aa 100644..100755
--- a/bin/values.rb
+++ b/bin/values.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 ##
 # Generate the different values on `config/values/*.s` by parsing the values on
@@ -19,7 +20,8 @@ config = YAML.safe_load_file(File.join(config_path, 'values.yml'))
 # 4.4 format.
 def to_signed_fixed_point(value)
   integer = value.to_i
-  raise "bad signed fixed point value" if integer > 7 || integer < -7
+  raise 'bad signed fixed point value' if integer > 7 || integer < -7
+
   integer &= 0b00001111
 
   decimal = (value % 1) * 100
@@ -58,23 +60,21 @@ def to_hex(value)
 end
 
 def values_to_asm(values)
-  contents = ""
-  values.each { |k, v| contents << "    #{k} = #{to_hex(v)}\n" }
-  contents.rstrip
+  values.map { |k, v| "    #{k} = #{to_hex(v)}" }.join("\n")
 end
 
 res.each do |model, formats|
   path = File.join(config_path, "values/#{model}.s")
-  contents = <<HERE
-;; This file has been automatically generated via bin/values.rb.
-;; DO NOT MODIFY this file directly: check config/values.yml instead.
-
-.ifdef PAL
-#{values_to_asm(formats[:pal])}
-.else
-#{values_to_asm(formats[:ntsc])}
-.endif
-HERE
-
-  File.open(path, 'w') { |f| f.write(contents) }
+  contents = <<~HERE
+    ;; This file has been automatically generated via bin/values.rb.
+    ;; DO NOT MODIFY this file directly: check config/values.yml instead.
+
+    .ifdef PAL
+    #{values_to_asm(formats[:pal])}
+    .else
+    #{values_to_asm(formats[:ntsc])}
+    .endif
+  HERE
+
+  File.write(path, contents)
 end
diff --git a/src/prng.s b/src/prng.s
index 8211957..d62392e 100644
--- a/src/prng.s
+++ b/src/prng.s
@@ -23,6 +23,8 @@
 
 
 ;; The pre-computed table.
+;;
+;; NOTE: generated via bin/rand.rb; read more on this there.
 valid_y_rand_table:
     .byte $25, $87, $B7, $6A, $23, $77, $6D, $71, $6D, $B6, $86, $93, $2B, $97, $A8, $39
     .byte $26, $AE, $A6, $70, $9F, $2D, $74, $B2, $8E, $A5, $33, $3E, $6D, $75, $91, $6B