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set proper flags for adc

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This commit is contained in:
Matthew Berry 2020-10-11 23:47:21 -07:00
parent ad446281fc
commit 3d0408d702
2 changed files with 14 additions and 1 deletions
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13
src/crab/cpu.cr
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@ -138,6 +138,19 @@ class CPU
res
end
# Add two values with carry
def adc(operand_1 : Word, operand_2 : Word, set_conditions) : Word
log "adc - operand_1:#{hex_str operand_1}, operand_2:#{hex_str operand_2}"
res = operand_1 &+ operand_2 &+ @cpsr.carry.to_unsafe
if set_conditions
@cpsr.overflow = bit?(~(operand_1 ^ operand_2) & (operand_2 ^ res), 31)
@cpsr.carry = res < operand_1
@cpsr.zero = res == 0
@cpsr.negative = bit?(res, 31)
end
res
end
def print_state(instr : Word) : Nil
{% if flag? :trace %}
@r.each do |reg|

2
src/crab/thumb/alu_operations.cr
View file

@ -10,7 +10,7 @@ module THUMB
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 0b0101 then res = @r[rd] = adc(@r[rd], @r[rs], true)
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]