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Added sign_extend template

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This commit is contained in:
John Wellbelove 2016-02-27 16:54:51 +00:00
parent 02aa427e6b
commit da8a31c19e
2 changed files with 105 additions and 0 deletions
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55
binary.h
View File

@ -35,6 +35,9 @@ SOFTWARE.
/// Binary utilities
///\ingroup utilities
#include <limits>
#include <assert.h>
#include "type_traits.h"
#include "integral_limits.h"
#include "static_assert.h"
@ -496,6 +499,58 @@ namespace etl
return folded_value;
}
//***************************************************************************
/// Sign extend.
/// Converts an N bit binary number, where bit N-1 is the sign bit, to a signed integral type.
//***************************************************************************
template <typename TReturn, const size_t NBITS, typename TValue>
TReturn sign_extend(TValue value)
{
STATIC_ASSERT(etl::is_integral<TValue>::value, "TValue not an integral type");
STATIC_ASSERT(etl::is_integral<TReturn>::value, "TReturn not an integral type");
STATIC_ASSERT(etl::is_signed<TReturn>::value, "TReturn not a signed type");
STATIC_ASSERT(NBITS <= std::numeric_limits<TReturn>::digits, "NBITS too large for return type");
typedef etl::make_unsigned<TReturn>::type mask_t;
mask_t negative = (1 << (NBITS - 1));
TReturn signed_value = value;
if ((signed_value & negative) != 0)
{
mask_t sign_bits = ~((1 << NBITS) - 1);
signed_value = value | sign_bits;
}
return signed_value;
}
//***************************************************************************
/// Sign extend.
/// Converts an N bit binary number, where bit N-1 is the sign bit, to a signed integral type.
//***************************************************************************
template <typename TReturn, typename TValue>
TReturn sign_extend(TValue value, const size_t NBITS)
{
STATIC_ASSERT(etl::is_integral<TValue>::value, "TValue not an integral type");
STATIC_ASSERT(etl::is_integral<TReturn>::value, "TReturn not an integral type");
STATIC_ASSERT(etl::is_signed<TReturn>::value, "TReturn not a signed type");
assert(NBITS <= std::numeric_limits<TReturn>::digits);
typedef etl::make_unsigned<TReturn>::type mask_t;
mask_t negative = (1 << (NBITS - 1));
TReturn signed_value = value;
if ((signed_value & negative) != 0)
{
mask_t sign_bits = ~((1 << NBITS) - 1);
signed_value = value | sign_bits;
}
return signed_value;
}
//***************************************************************************
/// 8 bit binary constants.
//***************************************************************************

50
test/test_binary.cpp
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@ -910,6 +910,56 @@ namespace
CHECK((std::is_same<uint64_t, etl::max_value_for_nbits<63>::value_type>::value));
CHECK((std::is_same<uint64_t, etl::max_value_for_nbits<64>::value_type>::value));
}
//*************************************************************************
TEST(test_sign_extend_template1)
{
uint8_t value8 = 0x2A;
value8 &= 0x3F; // 6 bit number.
CHECK_EQUAL(-22, (etl::sign_extend<int8_t, 6>(value8)));
CHECK_EQUAL(-22, (etl::sign_extend<int16_t, 6>(value8)));
CHECK_EQUAL(-22, (etl::sign_extend<int32_t, 6>(value8)));
CHECK_EQUAL(-22, (etl::sign_extend<int64_t, 6>(value8)));
uint16_t value16 = 0x2AAA;
value16 &= 0x3FFF; // 14 bit number.
CHECK_EQUAL(-5462, (etl::sign_extend<int16_t, 14>(value16)));
CHECK_EQUAL(-5462, (etl::sign_extend<int32_t, 14>(value16)));
CHECK_EQUAL(-5462, (etl::sign_extend<int64_t, 14>(value16)));
uint32_t value32 = 0x2AAAAAAA;
value32 &= 0x3FFFFFFF; // 30 bit number.
CHECK_EQUAL(-357913942, (etl::sign_extend<int32_t, 30>(value32)));
CHECK_EQUAL(-357913942, (etl::sign_extend<int64_t, 30>(value32)));
}
//*************************************************************************
TEST(test_sign_extend_template2)
{
uint8_t value8 = 0x2A;
value8 &= 0x3F; // 6 bit number.
CHECK_EQUAL(-22, (etl::sign_extend<int8_t>(value8, 6)));
CHECK_EQUAL(-22, (etl::sign_extend<int16_t>(value8, 6)));
CHECK_EQUAL(-22, (etl::sign_extend<int32_t>(value8, 6)));
CHECK_EQUAL(-22, (etl::sign_extend<int64_t>(value8, 6)));
uint16_t value16 = 0x2AAA;
value16 &= 0x3FFF; // 14 bit number.
CHECK_EQUAL(-5462, (etl::sign_extend<int16_t>(value16, 14)));
CHECK_EQUAL(-5462, (etl::sign_extend<int32_t>(value16, 14)));
CHECK_EQUAL(-5462, (etl::sign_extend<int64_t>(value16, 14)));
uint32_t value32 = 0x2AAAAAAA;
value32 &= 0x3FFFFFFF; // 30 bit number.
CHECK_EQUAL(-357913942, (etl::sign_extend<int32_t>(value32, 30)));
CHECK_EQUAL(-357913942, (etl::sign_extend<int64_t>(value32, 30)));
}
};
}