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88 lines
2.6 KiB
C++
88 lines
2.6 KiB
C++
#ifndef LIMONP_CAST_FUNCTS_H
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#define LIMONP_CAST_FUNCTS_H
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namespace Limonp
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{
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//logical and or
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static const int sign_32 = 0xC0000000;
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static const int exponent_32 = 0x07800000;
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static const int mantissa_32 = 0x007FE000;
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static const int sign_exponent_32 = 0x40000000;
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static const int loss_32 = 0x38000000;
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static const short sign_16 = (short)0xC000;
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static const short exponent_16 = (short)0x3C00;
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static const short mantissa_16 = (short)0x03FF;
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static const short sign_exponent_16 = (short)0x4000;
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static const int exponent_fill_32 = 0x38000000;
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//infinite
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static const short infinite_16 = (short) 0x7FFF;
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static const short infinitesmall_16 = (short) 0x0000;
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inline float intBitsToFloat(unsigned int x)
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{
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union
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{
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float f;
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int i;
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}u;
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u.i = x;
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return u.f;
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}
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inline int floatToIntBits(float f)
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{
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union
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{
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float f;
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int i ;
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}u;
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u.f = f;
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return u.i;
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}
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inline short floatToShortBits(float f)
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{
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int fi = floatToIntBits(f);
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// 提取关键信息
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short sign = (short) ((unsigned int)(fi & sign_32) >> 16);
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short exponent = (short) ((unsigned int)(fi & exponent_32) >> 13);
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short mantissa = (short) ((unsigned int)(fi & mantissa_32) >> 13);
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// 生成编码结果
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short code = (short) (sign | exponent | mantissa);
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// 无穷大量、无穷小量的处理
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if ((fi & loss_32) > 0 && (fi & sign_exponent_32) > 0) {
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// 当指数符号为1时(正次方)，且左234位为1，返回无穷大量
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return (short) (code | infinite_16);
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}
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if (((fi & loss_32) ^ loss_32) > 0 && (fi & sign_exponent_32) == 0) {
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// 当指数符号位0时(负次方)，且左234位为0(与111异或>0)，返回无穷小量
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return infinitesmall_16;
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}
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return code;
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}
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inline float shortBitsToFloat(short s)
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{
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/*
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* 指数空余3位：若符号位为1，补0；若符号位为0，补1。 尾数位在后补0(13个)
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*/
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int sign = ((int) (s & sign_16)) << 16;
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int exponent = ((int) (s & exponent_16)) << 13;
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// 指数符号位为0，234位补1
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if ((s & sign_exponent_16) == 0 && s != 0) {
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exponent |= exponent_fill_32;
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}
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int mantissa = ((int) (s & mantissa_16)) << 13;
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// 生成解码结果
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int code = sign | exponent | mantissa;
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return intBitsToFloat(code);
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}
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}
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#endif
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