move cpsr onto new bitfield implementation

.gitignore

@@ -3,3 +3,4 @@
 /bin/
 /.shards/
 *.dwarf
+/shard.lock

shard.yml

@@ -10,4 +10,9 @@ targets:
 
 crystal: 0.35.1
 
+dependencies:
+  bitfield:
+    github: mattrberry/bitfield
+    version: 0.1.0
+
 license: MIT

src/crab.cr

@@ -1,3 +1,5 @@
+require "bitfield"
+
 require "./crab/gba"
 
 module Crab

src/crab/arm/arm.cr

@@ -19,21 +19,21 @@ module ARM
 
   private def check_cond(cond : Word) : Bool
     case bits cond, 28..31
-    when 0x0 then bit?(@cpsr, 30)                                        # Z
-    when 0x1 then !bit?(@cpsr, 30)                                       # !Z
-    when 0x2 then bit?(@cpsr, 29)                                        # C
-    when 0x3 then !bit?(@cpsr, 29)                                       # !C
-    when 0x4 then bit?(@cpsr, 31)                                        # N
-    when 0x5 then !bit?(@cpsr, 31)                                       # !N
-    when 0x6 then bit?(@cpsr, 28)                                        # V
-    when 0x7 then !bit?(@cpsr, 28)                                       # !V
-    when 0x8 then bit?(@cpsr, 29) && !bit?(@cpsr, 30)                    # C && !Z
-    when 0x9 then !bit?(@cpsr, 29) || bit?(@cpsr, 30)                    # !C || Z
-    when 0xA then bit?(@cpsr, 31) == bit?(@cpsr, 28)                     # N == V
-    when 0xB then bit?(@cpsr, 31) != bit?(@cpsr, 28)                     # N != V
-    when 0xC then !bit?(@cpsr, 30) && bit?(@cpsr, 31) == bit?(@cpsr, 28) # !Z && N == V
-    when 0xD then bit?(@cpsr, 30) || bit?(@cpsr, 31) != bit?(@cpsr, 28)  # Z || N != V
-    when 0xE then true                                                   # always
+    when 0x0 then @cpsr.zero
+    when 0x1 then !@cpsr.zero
+    when 0x2 then @cpsr.carry
+    when 0x3 then !@cpsr.carry
+    when 0x4 then @cpsr.negative
+    when 0x5 then !@cpsr.negative
+    when 0x6 then @cpsr.overflow
+    when 0x7 then !@cpsr.overflow
+    when 0x8 then @cpsr.carry && !@cpsr.zero
+    when 0x9 then !@cpsr.carry || @cpsr.zero
+    when 0xA then @cpsr.negative == @cpsr.overflow
+    when 0xB then @cpsr.negative != @cpsr.overflow
+    when 0xC then !@cpsr.zero && @cpsr.negative == @cpsr.overflow
+    when 0xD then @cpsr.zero || @cpsr.negative != @cpsr.overflow
+    when 0xE then true
     else          raise "Cond 0xF is reserved"
     end
   end

src/crab/arm/data_processing.cr

@@ -19,9 +19,9 @@ module ARM
     when 0x2 then @r[rd] = rn &- operand_2
     when 0x3 then @r[rd] = operand_2 &- rn
     when 0x4 then @r[rd] = rn &+ operand_2
-    when 0x5 then @r[rd] = rn &+ operand_2 &+ (bit?(@cpsr, 29) ? 1 : 0)
-    when 0x6 then @r[rd] = rn &- operand_2 &+ (bit?(@cpsr, 29) ? 1 : 0) &- 1
-    when 0x7 then @r[rd] = operand_2 &- rn &+ (bit?(@cpsr, 29) ? 1 : 0) &- 1
+    when 0x5 then @r[rd] = rn &+ operand_2 &+ @cpsr.carry.to_unsafe
+    when 0x6 then @r[rd] = rn &- operand_2 &+ @cpsr.carry.to_unsafe &- 1
+    when 0x7 then @r[rd] = operand_2 &- rn &+ @cpsr.carry.to_unsafe &- 1
     when 0x8
     when 0x9
     when 0xA

src/crab/cpu.cr

@@ -3,8 +3,20 @@ require "./arm/*"
 class CPU
   include ARM
 
+  class PSR < BitField(UInt32)
+    bool negative
+    bool zero
+    bool carry
+    bool overflow
+    num reserved, 20
+    bool irq_disable
+    bool fiq_disable
+    bool thumb
+    num mode, 5
+  end
+
   @r = Slice(Word).new 16
-  @cpsr : UInt32 = 0
+  @cpsr : PSR
   @pipeline = Deque(Word).new 2
   getter lut : Slice(Proc(Word, Nil)) { fill_lut }
 
@@ -13,7 +25,7 @@ class CPU
     @r[1] = 0x000000EA
     @r[13] = 0x03007F00
     @r[15] = 0x08000000
-    @cpsr = 0x6000001F
+    @cpsr = PSR.new 0x6000001F
   end
 
   def fill_pipeline : Nil
@@ -40,6 +52,6 @@ class CPU
     @r.each do |reg|
       trace "#{hex_str reg, prefix: false} ", newline: false
     end
-    trace "cpsr: #{hex_str @cpsr, prefix: false} | #{hex_str instr, prefix: false}"
+    trace "cpsr: #{hex_str @cpsr.value, prefix: false} | #{hex_str instr, prefix: false}"
   end
 end