def farith(s, inst):
"""
RD = RN <OP> RM
BN = RD[31]
if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
if (UnbiasedExponent(RD) > 127) { BUV=1 } else { BV=0 }
if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
BVS = BVS | BV;
"""
if is16bit:
inst.bits &= 0xffff
rd = bits2float(s.rf[inst.rd])
rn = bits2float(s.rf[inst.rn])
rm = bits2float(s.rf[inst.rm])
# Binary operations.
if name == 'add':
result = rn + rm
elif name == 'sub':
result = rn - rm
elif name == 'mul':
result = rn * rm
elif name == 'madd':
result = rd + (rn * rm)
elif name == 'msub':
result = rd - (rn * rm)
# Unary operations.
elif name == 'float':
result = float(s.rf[inst.rn])
elif name == 'fix':
if math.isnan(rn): # FXIME
result = 0xffffffff
else:
result = int(rn)
elif name == 'abs':
result = abs(rn)
# 'result' is always a Python float.
# RD = RN <OP> RM
s.rf[inst.rd] = trim_32(result if name == 'fix' else float2bits(result))
# BN = RD[31]
s.BN = True if result < 0.0 else False
# if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
s.BZ = True if abs(result) < 0.0001 else False
# if (UnbiasedExponent(RD) > 127) { BUV=1 } else { BV=0 }
s.BUV = True if get_exponent(s.rf[inst.rd]) > 127 else False
# if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
if get_exponent(s.rf[inst.rd]) > 127:
s.BUS = True
# if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
if ((is_unary and math.isnan(rn)) or
(not is_unary) and
(math.isnan(rn) or math.isnan(rm))):
s.BIS = True
# BVS = BVS | BV;
s.BVS = s.BVS or s.BV
s.debug_flags()
s.pc += 2 if is16bit else 4
def test_get_exponent():
bits = 0b01111111100000000000000000000000
assert get_exponent(bits) == 0xFF
bits = 0b11111111100000000000000000000000
assert get_exponent(bits) == 0xFF
bits = 0b00000000011111111111111111111111
assert get_exponent(bits) == 0
bits = 0b10000000011111111111111111111111
assert get_exponent(bits) == 0