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144 lines
2.6 KiB
144 lines
2.6 KiB
#pragma once
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#include <cstdint>
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#include <cmath>
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class bfloat16
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{
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uint16_t value;
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union FloatBits
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{
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float f;
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uint16_t s[2];
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uint32_t i;
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};
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bfloat16(uint16_t x, bool) : value(x)
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{}
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public:
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bfloat16() = default;
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bfloat16(float x)
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{
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*this = x;
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}
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bfloat16& operator = (float x)
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{
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FloatBits b {x};
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switch(std::fpclassify(x))
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{
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case FP_SUBNORMAL:
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case FP_ZERO:
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// sign preserving zero (denormal go to zero)
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value = b.s[1];
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value &= 0x8000;
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break;
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case FP_INFINITE:
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value = b.s[1];
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break;
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case FP_NAN:
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// truncate and set MSB of the mantissa force QNAN
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value = b.s[1];
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value |= 1 << 6;
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break;
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case FP_NORMAL:
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// round to nearest even and truncate
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unsigned int rounding_bias = 0x00007FFF + (b.s[1] & 0x1);
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b.i += rounding_bias;
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value = b.s[1];
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break;
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}
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return *this;
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}
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operator float() const
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{
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FloatBits b {0};
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b.s[1] = value;
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return b.f;
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}
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inline bfloat16 operator - () const
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{
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return bfloat16(value ^ 0x8000, true);
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}
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};
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inline bfloat16 operator + (bfloat16 a, bfloat16 b)
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{
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return float(a) + float(b);
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}
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inline bfloat16 operator - (bfloat16 a, bfloat16 b)
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{
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return float(a) + float(-b);
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}
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inline bfloat16 operator * (bfloat16 a, bfloat16 b)
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{
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return float(a) * float(b);
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}
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inline bfloat16 operator / (bfloat16 a, bfloat16 b)
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{
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return float(a) / float(b);
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}
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inline bfloat16& operator += (bfloat16& a, const bfloat16 b)
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{
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a = a + b;
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return a;
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}
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inline bfloat16& operator -= (bfloat16& a, const bfloat16 b)
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{
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a = a - b;
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return a;
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}
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inline bfloat16& operator *= (bfloat16& a, const bfloat16 b)
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{
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a = a * b;
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return a;
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}
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inline bfloat16& operator /= (bfloat16& a, const bfloat16 b)
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{
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a = a / b;
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return a;
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}
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// Comparison operators
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inline bfloat16 operator == (const bfloat16 a, const bfloat16 b)
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{
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return float(a) == float(b);
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}
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inline bfloat16 operator != (const bfloat16 a, const bfloat16 b)
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{
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return !(a == b);
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}
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inline bfloat16 operator < (const bfloat16 a, const bfloat16 b)
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{
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return float(a) < float(b);
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}
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inline bfloat16 operator <= (const bfloat16 a, const bfloat16 b)
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{
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return float(a) <= float(b);
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}
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inline bfloat16 operator > (const bfloat16 a, const bfloat16 b)
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{
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return float(a) > float(b);
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}
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inline bfloat16 operator >= (const bfloat16 a, const bfloat16 b)
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{
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return float(a) >= float(b);
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}
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