96 lines
3.9 KiB
Ruby
96 lines
3.9 KiB
Ruby
module Arm
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# ADDRESSING MODE 2
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# Implemented: immediate offset with offset=0
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class MemoryInstruction < Register::Instruction
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include Constants
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include Attributed
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def initialize result , left , right = nil , attributes = {}
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super(nil)
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@attributes = attributes
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@result = result
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@left = left
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@right = right
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@attributes[:update_status] = 1 if @attributes[:update_status] == nil
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@attributes[:condition_code] = :al if @attributes[:condition_code] == nil
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@operand = 0
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raise "alert" if right.is_a? Register::Label
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@pre_post_index = @attributes[:pre_post_index] ? 0 : 1 #P flag
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@add_offset = @attributes[:add_offset] ? 0 : 1 #U flag
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@is_load = opcode.to_s[0] == "l" ? 1 : 0 #L (load) flag
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end
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def assemble(io)
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# don't overwrite instance variables, to make assembly repeatable
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rn , operand , add_offset , arg = @rn , @operand , @add_offset , @left
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arg = arg.symbol if( arg.is_a? ::Register::RegisterValue )
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#str / ldr are _serious instructions. With BIG possibilities not half are implemented
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is_reg = arg.is_a?(::Register::RegisterValue)
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if( arg.is_a?(Symbol) and not is_reg)
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is_reg = (arg.to_s[0] == "r")
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end
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if (is_reg ) #symbol is register
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rn = arg
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if @right
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operand = @right
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#TODO better test, this operand integer (register) does not work. but sleep first
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operand = operand.symbol if operand.is_a? ::Register::RegisterValue
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unless( operand.is_a? Symbol) #TODO test/check/understand
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add_offset = (operand < 0) ? 0 : 1
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operand *= -1 if (operand < 0)
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raise "offset too large (max 4095) #{arg} #{inspect}" if (@operand.abs > 4095)
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end
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end
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elsif (arg.is_a?(Parfait::Object) or arg.is_a? Symbol ) #use pc relative
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rn = :pc
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operand = arg.position - self.position - 8 #stringtable is after code
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add_offset = 1
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if (operand.abs > 4095)
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raise "reference offset too large/small (4095<#{operand}) #{arg} #{inspect}"
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end
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else
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raise "invalid operand argument #{arg.inspect} #{inspect}"
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end
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#not sure about these 2 constants. They produce the correct output for str r0 , r1
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# but i can't help thinking that that is because they are not used in that instruction and
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# so it doesn't matter. Will see
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instuction_class = 0b01 # OPC_MEMORY_ACCESS
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if (operand.is_a?(Symbol) or operand.is_a?(::Register::RegisterValue))
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val = reg_code(operand)
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@pre_post_index = 0
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i = 1 # not quite sure about this, but it gives the output of as. read read read.
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else
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i = 0 #I flag (third bit)
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val = operand
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end
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# testing against gnu as, setting the flag produces correct output
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# but gnu as produces same output for auto_inc or not, so that seems broken
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# luckily auto_inc is not used and even if it clobbers unused reg in soml, but still
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@pre_post_index = 1
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op = shift_handling
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val = shift(val , 0 ) # for the test
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val |= shift(op , 0)
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val |= shift(reg_code(@result) , 12 )
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val |= shift(reg_code(rn) , 12 + 4) #16
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val |= shift(@is_load , 12 + 4 + 4)
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val |= shift(0 , 12 + 4 + 4 + 1)
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val |= shift(byte_access , 12 + 4 + 4 + 1 + 1)
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val |= shift(add_offset , 12 + 4 + 4 + 1 + 1 + 1)
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val |= shift(@pre_post_index, 12 + 4 + 4 + 1 + 1 + 1 + 1)#24
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val |= shift(i , 12 + 4 + 4 + 1 + 1 + 1 + 1 + 1)
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val |= shift(instuction_class,12 + 4 + 4 + 1 + 1 + 1 + 1 + 1 + 1)
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val |= shift(cond_bit_code , 12 + 4 + 4 + 1 + 1 + 1 + 1 + 1 + 1 + 2)
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io.write_uint32 val
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end
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def add_offset
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@attributes[:add_offset] ? 0 : 1
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end
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def byte_access
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opcode.to_s[-1] == "b" ? 1 : 0 #B (byte) flag
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end
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end
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end
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