thumb conditional branch, fix reg rotation, thumb/arm abstraction

src/crab/arm/arm.cr

@@ -17,27 +17,6 @@ module ARM
     (instr >> 16 & 0x0FF0) | (instr >> 4 & 0xF)
   end
 
-  private def check_cond(cond : Word) : Bool
-    case bits cond, 28..31
-    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
-
   def fill_lut : Slice(Proc(Word, Nil))
     lut = Slice(Proc(Word, Nil)).new 4096, ->arm_unimplemented(Word)
     4096.times do |idx|
@@ -89,26 +68,6 @@ module ARM
     puts "Unused instruction: #{hex_str instr}"
   end
 
-  # Logical shift left
-  def lsl(word : Word, bits : Int) : Word
-    word << bits
-  end
-
-  # Logical shift right
-  def lsr(word : Word, bits : Int) : Word
-    word >> bits
-  end
-
-  # Arithmetic shift right
-  def asr(word : Word, bits : Int) : Word
-    word // (2 ** bits)
-  end
-
-  # Rotate right
-  def ror(word : Word, bits : Int) : Word
-    word >> bits | word << (32 - bits)
-  end
-
   def rotate_register(instr : Word, allow_register_shifts = true) : Word
     reg = bits(instr, 0..3)
     shift_type = bits(instr, 5..6)
@@ -120,10 +79,10 @@ module ARM
                      bits(instr, 7..11)
                    end
     case shift_type
-    when 0b00 then lsl(reg, shift_amount)
-    when 0b01 then lsr(reg, shift_amount)
-    when 0b10 then asr(reg, shift_amount)
-    when 0b11 then ror(reg, shift_amount)
+    when 0b00 then lsl(@r[reg], shift_amount)
+    when 0b01 then lsr(@r[reg], shift_amount)
+    when 0b10 then asr(@r[reg], shift_amount)
+    when 0b11 then ror(@r[reg], shift_amount)
     else           raise "Impossible shift type: #{hex_str shift_type}"
     end
   end

src/crab/cpu.cr

@@ -61,6 +61,47 @@ class CPU
     end
   end
 
+  def check_cond(cond : Word) : Bool
+    case bits cond, 28..31
+    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
+
+  # Logical shift left
+  def lsl(word : Word, bits : Int) : Word
+    word << bits
+  end
+
+  # Logical shift right
+  def lsr(word : Word, bits : Int) : Word
+    word >> bits
+  end
+
+  # Arithmetic shift right
+  def asr(word : Word, bits : Int) : Word
+    word // (2 ** bits)
+  end
+
+  # Rotate right
+  def ror(word : Word, bits : Int) : Word
+    word >> bits | word << (32 - bits)
+  end
+
   def print_state(instr : Word) : Nil
     {% if flag? :trace %}
       @r.each do |reg|

src/crab/thumb/conditional_branch.cr

@@ -0,0 +1,10 @@
+module THUMB
+  def thumb_conditional_branch(instr : Word) : Nil
+    cond = bits(instr, 8..11)
+    offset = bits(instr, 0..8).to_i8!
+    if cond
+      @r[15] &+= (offset * 2)
+      clear_pipeline
+    end
+  end
+end

src/crab/thumb/move_shifted_register.cr

@@ -6,9 +6,9 @@ module THUMB
     rs = bits(instr, 3..5)
     rd = bits(instr, 0..2)
     @r[rd] = case op
-             when 0b00 then @r[rs] << offset
-             when 0b01 then @r[rs] >> offset
-             when 0b10 then @r[rs] // (2 ** offset)
+             when 0b00 then lsl(@r[rs], offset)
+             when 0b01 then lsr(@r[rs], offset)
+             when 0b10 then asr(@r[rs], offset)
              else           raise "Invalid shifted register op: #{op}"
              end
     @cpsr.zero = @r[rd] == 0

src/crab/thumb/thumb.cr

@@ -13,7 +13,7 @@ module THUMB
       elsif idx & 0b11111111 == 0b11011111
         # software interrupt
       elsif idx & 0b11110000 == 0b11010000
-        # conditional branch
+        lut[idx] = ->thumb_conditional_branch(Word)
       elsif idx & 0b11110000 == 0b11000000
         # multiple load/store
       elsif idx & 0b11110110 == 0b10110100