diff --git a/lib/arm/move_instruction.rb b/lib/arm/move_instruction.rb index add3c29f..33b30d01 100644 --- a/lib/arm/move_instruction.rb +++ b/lib/arm/move_instruction.rb @@ -16,7 +16,7 @@ module Arm @extra = nil end - # arm intrucions are pretty sensible, and always 4 bytes (thumb not supported) + # arm intructions are pretty sensible, and always 4 bytes (thumb not supported) # but not all constants fit into the part of the instruction that is left after the instruction code, # so large moves have to be split into two instructions. # we handle this "transparently", just this instruction looks longer @@ -39,8 +39,11 @@ module Arm # 8 is for the funny pipeline adjustment (ie pc pointing to fetch and not execute) right = Virtual::IntegerConstant.new( r_pos - self.position - 8 ) #puts "Position #{r_pos} from #{self.position} = #{right}" - right = Virtual::IntegerConstant.new(r_pos) if right.integer > 255 - rn = :pc + if right.integer > 255 + right = Virtual::IntegerConstant.new(r_pos) + else + rn = :pc + end end if (right.is_a?(Virtual::IntegerConstant)) if (right.fits_u8?) @@ -52,26 +55,29 @@ module Arm immediate = 1 else # unfortunately i was wrong in thinking the pi is armv7. The good news is the code below implements - # the movw (armv7) instruciton and works + # the movw instruction (armv7 for moving a word) and works #armv7 raise "Too big #{right.integer} " if (right.integer >> 16) > 0 #armv7 operand = (right.integer & 0xFFF) #armv7 immediate = 1 #armv7 rn = (right.integer >> 12) - # a little STRANGE, that the armv7 movw (move a 2 byte word) is an old test opcode, but there it is - #armv7 @attributes[:opcode] = :tst - raise "No negatives implemented " if right.integer < 0 + # a little STRANGE, that the armv7 movw (move a 2 byte word) is an old test opcode, but there it is + #armv7 @attributes[:opcode] = :tst + raise "No negatives implemented #{right} " if right.integer < 0 # and so it continues: when we notice that the const doesn't fit, first time we raise an # error,but set the extra flag, to say the instruction is now 8 bytes - # then on subsequent assemlies we can assemble + # then on subsequent assemblies we can assemble unless @extra @extra = 1 raise ::Register::LinkException.new("cannot fit numeric literal argument in operand #{right.inspect}") end - # now we can do the actual breaking of instruction - operand = (right.integer / 256 ) + # now we can do the actual breaking of instruction, by splitting the operand + first = Virtual::IntegerConstant.new(right.integer & 0xFFFFFF00) + operand = calculate_u8_with_rr( first ) + raise "no fit for #{right}" unless operand immediate = 1 - raise "only simple 2 byte implemented #{self.inspect}" if operand > 255 - @extra = ::Register::RegisterMachine.instance.add( to , to , (right.integer && 0xFF) , shift_lsr: 8) + @extra = ::Register::RegisterMachine.instance.add( to , to , (right.integer & 0xFF) ) + #TODO: this is still a hack, as it does not encode all possible values. The way it _should_ be done + # is to check that the first part is doabe with u8_with_rr AND leaves a u8 remainder end elsif (right.is_a?(Symbol) or right.is_a?(::Register::RegisterReference)) operand = reg_code(right) @@ -94,7 +100,7 @@ module Arm # by now we have the extra add so assemble that if(@extra) @extra.assemble(io) - #puts "Assemble extra at #{self.position.to_s(16)}" + #puts "Assemble extra at #{val.to_s(16)}" end end def shift val , by diff --git a/test/arm/test_move.rb b/test/arm/test_move.rb index a47965c2..9309bcb0 100644 --- a/test/arm/test_move.rb +++ b/test/arm/test_move.rb @@ -4,12 +4,12 @@ class TestMoves < MiniTest::Test include ArmHelper def test_mov - code = @machine.mov :r0, 5 - assert_code code , :mov , [0x05,0x00,0xa0,0xe3] #e3 a0 10 05 + code = @machine.mov :r1, 5 + assert_code code , :mov , [0x05,0x10,0xa0,0xe3] #e3 a0 10 05 end def test_mov_pc - code = @machine.mov :pc, 6 - assert_code code , :mov , [0x06,0xf0,0xa0,0xe3] #e3 a0 f0 06 + code = @machine.mov :pc, 5 + assert_code code , :mov , [0x05,0xf0,0xa0,0xe3] #e3 a0 f0 06 end def test_mov_256 code = @machine.mov :r1, 256 @@ -20,10 +20,10 @@ class TestMoves < MiniTest::Test assert_code code , :mov , [0x80,0x10,0xa0,0xe3] #e3 a0 10 80 end def test_mov_big - code = @machine.mov :r0, 0x222 + code = @machine.mov :r0, 0x222 # is not 8 bit and can't be rotated by the arm system in one instruction code.set_position(0) - begin #TODO use compiler to confirm codes here: this is just what passes - assert_code code , :mov , [ 0x02,0x00,0xa0,0xe3 , 0xff,0x04,0x80,0xe2] + begin # mov 512(0x200) = e3 a0 0c 02 add 34(0x22) = e2 80 00 22 + assert_code code , :mov , [ 0x02,0x0c,0xa0,0xe3 , 0x22,0x00,0x80,0xe2] rescue Register::LinkException retry end @@ -32,4 +32,22 @@ class TestMoves < MiniTest::Test code = @machine.mvn :r1, 5 assert_code code , :mvn , [0x05,0x10,0xe0,0xe3] #e3 e0 10 05 end + def test_constant_small # like test_mov + const = Virtual::ObjectConstant.new + const.set_position( 13 ) # 13 = 5 + 8 , 8 for the arm pipeline offset, gets subtracted + code = @machine.mov :r1 , const + code.set_position(0) + assert_code code , :mov , [0x05,0x10,0xaf,0xe3] #e3 ef 10 05 + end + def test_constant_big # like test_mov_big + const = Virtual::ObjectConstant.new + const.set_position( 0x222 ) + code = @machine.mov :r0 , const + code.set_position(0) + begin # mov 512(0x200) = e3 a0 0c 02 add 34(0x22) = e2 80 00 22 + assert_code code , :mov , [ 0x02,0x0c,0xa0,0xe3 , 0x22,0x00,0x80,0xe2] + rescue Register::LinkException + retry + end + end end