Miroirs/crab
1
0
Fork 0
mirror of https://github.com/mattrberry/crab.git synced 2024-12-29 10:23:54 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

simplify register rotates a little bit

Browse source
This commit is contained in:
Matthew Berry 2021-05-02 19:08:06 -07:00
parent 655bd67855
commit b8a7fc1428
1 changed files with 4 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
src/crab/arm/arm.cr
View file

@ -72,14 +72,13 @@ module ARM
def rotate_register(instr : Word, carry_out : Pointer(Bool), allow_register_shifts : Bool) : Word
reg = bits(instr, 0..3)
shift_type = bits(instr, 5..6)
if allow_register_shifts && bit?(instr, 4)
immediate = !(allow_register_shifts && bit?(instr, 4))
if immediate
shift_amount = bits(instr, 7..11)
else
shift_register = bits(instr, 8..11)
# todo weird logic if bottom byte of reg > 31
shift_amount = @r[shift_register] & 0xFF
immediate = false
else
shift_amount = bits(instr, 7..11)
immediate = true
end
case shift_type
when 0b00 then lsl(@r[reg], shift_amount, carry_out)