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thumb alu operations

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This commit is contained in:
Matthew Berry 2020-09-27 23:32:14 -07:00
parent 7820e69eb6
commit ac7e3bbe72
2 changed files with 29 additions and 1 deletions
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28
src/crab/thumb/alu_operations.cr Normal file
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@ -0,0 +1,28 @@
module THUMB
def thumb_alu_operations(instr : Word) : Nil
op = bits(instr, 6..9)
rs = bits(instr, 3..5)
rd = bits(instr, 0..2)
case op
when 0b0000 then res = @r[rd] = @r[rd] & @r[rs]
when 0b0001 then res = @r[rd] = @r[rd] ^ @r[rs]
when 0b0010 then res = @r[rd] = lsl(@r[rd], @r[rs], true)
when 0b0011 then res = @r[rd] = lsr(@r[rd], @r[rs], true)
when 0b0100 then res = @r[rd] = asr(@r[rd], @r[rs], true)
when 0b0101 then res = @r[rd] = @r[rd] &+ @r[rs] &+ @cpsr.carry.to_unsafe
when 0b0110 then res = @r[rd] = @r[rd] &- @r[rs] &- ~@cpsr.carry.to_unsafe
when 0b0111 then res = @r[rd] = ror(@r[rd], @r[rs], true)
when 0b1000 then res = @r[rd] & @r[rs]
when 0b1001 then res = @r[rd] = (-@r[rs].to_i32!).to_u32!
when 0b1010 then res = @r[rd] &- @r[rs]
when 0b1011 then res = @r[rd] &+ @r[rs]
when 0b1100 then res = @r[rd] = @r[rd] | @r[rs]
when 0b1101 then res = @r[rd] = @r[rs] * @r[rd]
when 0b1110 then res = @r[rd] = @r[rd] & ~@r[rs]
when 0b1111 then res = @r[rd] = ~@r[rs]
else raise "Invalid alu op: #{op}"
end
@cpsr.zero = res == 0
@cpsr.negative = bit?(res, 31)
end
end

2
src/crab/thumb/thumb.cr
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@ -37,7 +37,7 @@ module THUMB
elsif idx & 0b11111100 == 0b01000100
# hi register operations / branch exchange
elsif idx & 0b11111100 == 0b01000000
# alu operations
lut[idx] = ->thumb_alu_operations(Word)
elsif idx & 0b11100000 == 0b00100000
lut[idx] = ->thumb_move_compare_add_subtract(Word)
elsif idx & 0b11111100 == 0b00011000