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Removes dead code from IBMFloat.

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Robert Smallshire
2015-05-06 12:51:39 +02:00
parent 05ecd3423e
commit b0e02e2f8e
1 changed files with 1 additions and 38 deletions
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segpy/ibm_float.py
+1 -38
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@@ -49,47 +49,10 @@ def ibm2ieee(big_endian_bytes):
value = sign * mantissa * pow(16, exponent_16_biased - EXPONENT_BIAS)
return value
BITS_PER_NYBBLE = 4
def truncate(big_endian_bytes):
a, b, c, d = four_bytes(big_endian_bytes)
sign = -1 if (a & 0x80) else 1
exponent_16_biased = a & 0x7f
exponent_16 = exponent_16_biased - EXPONENT_BIAS
mantissa = ((b << 16) | (c << 8) | d)
print("sign =", sign)
print("exponent_16", exponent_16, hex(exponent_16), bin(exponent_16))
print("mantissa", mantissa, hex(mantissa), bin(mantissa))
num_nybbles_to_preserve = min(exponent_16, MAX_BITS_PRECISION_IBM_FLOAT // BITS_PER_NYBBLE)
num_bits_to_clear = MAX_BITS_PRECISION_IBM_FLOAT - num_nybbles_to_preserve * BITS_PER_NYBBLE
clear_mask = 2**num_bits_to_clear - 1
preserve_mask = (2**MAX_BITS_PRECISION_IBM_FLOAT - 1) & ~clear_mask
print("num_nybbles_to_preserve", num_nybbles_to_preserve)
print("num_bits_to_clear", num_bits_to_clear)
print("clear_mask ", bin(clear_mask))
print("preserve_mask", bin(preserve_mask))
truncated_mantissa = mantissa & preserve_mask
value = truncated_mantissa * pow(16, exponent_16)
scaled_value = value >> MAX_BITS_PRECISION_IBM_FLOAT
return scaled_value
#
# tb = (preserve_mask >> 16) & b
# tc = (preserve_mask >> 8) & c
# td = preserve_mask & d
#
# return byte_string((a, tb, tc, td))
def ieee2ibm(f):
"""Convert a float to four big-endian bytes representing an IBM float.