124 lines
3.2 KiB
C++
124 lines
3.2 KiB
C++
/*******************************************************************************
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HARPtools by Chad D. Kersey, Summer 2011
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*******************************************************************************/
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#include <math.h>
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#include <stdlib.h>
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#include "types.h"
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#ifdef DEBUG
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#include <iostream>
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#define DEBUGMSG(x) do { \
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std::cout << __FILE__ << ':' <<__LINE__ << ": " << x << '\n'; \
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} while(0)
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#else
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#define DEBUGMSG(x) do { } while(0)
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#endif
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namespace Harp {
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// This class serves to handle the strange-precision floating point that can
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// crop up in HARP.
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class Float {
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public:
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Float(Word_u bin, Size n): sz(n) {
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DEBUGMSG("Float(0x" << std::hex << bin << ", " << std::dec << n << ')');
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bool sign(bin >> (n*8 - 1));
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Size expSz;
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if (n < 4) {
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expSz = 5;
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} else if (n < 8) {
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expSz = 8;
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} else {
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expSz = 11;
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}
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Size sigSz = n*8 - expSz - 1;
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DEBUGMSG(" exp: " << std::dec << expSz <<
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" bits, sig: " << std::dec << sigSz << " bits.");
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int exp = (bin >> sigSz) & ((1<<expSz) - 1);
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Word_u sig = bin & ((1llu<<sigSz) - 1);
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DEBUGMSG(" sig=" << std::dec << sig << " exp=" << exp);
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if (exp == 0) {
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// Subnormal
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d = sig / pow(2, ((1<<(expSz-1))-2)) / pow(2, sigSz);
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DEBUGMSG(" Denorm.");
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} else if (exp == ((1<<expSz) - 1)) {
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// Infinity
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d = HUGE_VAL;
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DEBUGMSG(" Inf.");
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} else {
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// Normalized, implied 1.
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exp -= (1<<(expSz - 1)) - 1;
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d = pow(2.0, exp - int(sigSz)) * double((1ll << sigSz) + sig);
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DEBUGMSG(" Norm, exp=" << exp);
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}
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if (sign) d = -d;
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DEBUGMSG("Set to " << d);
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}
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Float(double d, Size n): sz(n), d(d) { DEBUGMSG("Float(double, size)"); }
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operator Word_u() {
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DEBUGMSG("Float -> Word_u: " << d);
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Size expSz;
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if (sz < 4) {
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expSz = 5;
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} else if (sz < 8) {
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expSz = 8;
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} else {
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expSz = 11;
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}
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Size sigSz = 8*sz - expSz - 1;
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bool sign(d < 0);
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bool inf(isinf(d)), zero(d == 0.0);
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int exp;
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if (!inf && !zero) exp = floor(log2(fabs(d)));
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Word_u rval;
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if (inf) {
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// Infinity
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DEBUGMSG(" Inf.");
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rval = ((1llu<<expSz)-1llu)<<sigSz;
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} else if (!zero && abs(exp) < (1<<(expSz-1)) - 1) {
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// Normalized with implied 1.
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Word_u sig = (fabs(d) * pow(2.0, -exp) - 1.0) * pow(2.0, sigSz);
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DEBUGMSG(" Norm, exp=" << exp << ", sig=" << sig);
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rval = ((((exp + ((1llu<<(expSz-1)) - 1llu))
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&((1llu<<expSz)-1llu)))<<sigSz) | sig;
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} else if (!zero && exp > -(1<<(expSz-1)) - sigSz) {
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// Subnormal number.
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Word_u sig = round(fabs(d)*pow(2.0,((1<<(expSz-1))-2))*pow(2.0, sigSz));
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DEBUGMSG(" Denorm, exp=" << exp << ", sig=" << sig);
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rval = sig;
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} else {
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// Zero.
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rval = 0;
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}
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if (sign) rval |= 1llu<<(sz*8 - 1);
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DEBUGMSG(" Returning 0x" << std::hex << rval);
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return rval;
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}
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operator double() { DEBUGMSG("Float->double " << d); return d; }
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private:
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double d;
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Size sz;
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};
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};
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