mpw/toolbox/sane.cpp

/*
 * Copyright (c) 2013, Kelvin W Sherlock
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "qd.h"
#include "toolbox.h"
#include "sane.h"

#include <cpu/defs.h>
#include <cpu/CpuModule.h>
#include <cpu/fmem.h>

#include <stdlib.h>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>

#include "stackframe.h"
#include "complex.h"
#include "fpinfo.h"

using ToolBox::Log;


namespace SANE
{

using std::to_string;
using std::fpclassify;
using std::signbit;
using std::abs;

using its_complicated::to_string;
using its_complicated::fpclassify;
using its_complicated::signbit;

	namespace {
		// default environment is:
		// rounding direction: to nearest
		// rounding precision: extended
		// exception flags: clear
		// halts: clear

		/*
		 * Environment: x d d e e e e e x p p h h h h h
		 * x   - reserved
		 * d d - rounding direction
		 * e   - exception flags
		 * p   - rounding precision
		 * h   - halt flags
		 */

		enum {

			kExceptionInexact = 1 << 12,
			kExceptionDivideByZero = 1 << 11,
			kExceptionOverflow = 1 << 10,
			kExceptionUnderflow = 1 << 9,
			kExceptionInvalid = 1 << 8,

			kHaltInexact = 1 << 4,
			kHaltDivideByZero = 1 << 3,
			kHaltOverflow = 1 << 2,
			kHaltUnderflow = 1 << 1,
			kHaltInvalid = 1 << 0,

			kRoundingDirectionMask = 0x6000,
			kRoundingDirectionToNearest = 0x0000,
			kRoundingDirectionUpward = 0x2000,
			kRoundingDirectionDownward = 0x4000,
			kRoundingDirectionTowardZero = 0x6000,

			kRoundingPrecisionMask = 0x0060,
			kRoundingPrecisionExtended = 0x0000,
			kRoundingPrecisionDouble = 0x0020,
			kRoundingPrecisionSingle = 0x0040,
			kRoundingPrecisionUndefined = 0x0060,
		};


		const uint16_t DefaultEnvironment = 0;

		uint16_t Environment = DefaultEnvironment;





	}

	// long double is an 80-bit extended with an extra 48-bits of 0 padding.
	typedef long double extended;



	template <class T>
	T readnum(uint32_t address);

	template<>
	int16_t readnum<int16_t>(uint32_t address)
	{
		return memoryReadWord(address);
	}

	template<>
	int32_t readnum<int32_t>(uint32_t address)
	{
		return memoryReadLong(address);
	}


	template<>
	int64_t readnum<int64_t>(uint32_t address)
	{
		return memoryReadLongLong(address);
	}


	template<>
	complex readnum<complex>(uint32_t address)
	{
		return complex(memoryReadLongLong(address));
	}


	template<>
	float readnum<float>(uint32_t address)
	{
		static_assert(sizeof(float) == 4, "unexpected float size");

		uint32_t x = memoryReadLong(address);
		return *((float *)&x);
	}

	template<>
	double readnum<double>(uint32_t address)
	{
		static_assert(sizeof(double) == 8, "unexpected double size");

		uint64_t x = memoryReadLongLong(address);
		return *((double *)&x);
	}

	template<>
	long double readnum<long double>(uint32_t address)
	{
		uint8_t buffer[16];

		static_assert(sizeof(long double) == 16 || sizeof(long double) == 12, "unexpected long double size");

		// read and swap 10 bytes
		// this is very much little endian.

		for (unsigned i = 0; i < 10; ++i)
		{
			buffer[9 - i] = memoryReadByte(address + i);
		}
		// remainder are 0-filled.
		for (unsigned i = 10; i < 16; ++i)
			buffer[i] = 0;

		// now cast...


		return *((long double *)buffer);
	}


	template<class T>
	void writenum(T value, uint32_t address);

	template<>
	void writenum<int16_t>(int16_t value, uint32_t address)
	{
		memoryWriteWord(value, address);
	}

	template<>
	void writenum<int32_t>(int32_t value, uint32_t address)
	{
		memoryWriteLong(value, address);
	}

	template<>
	void writenum<int64_t>(int64_t value, uint32_t address)
	{
		memoryWriteLongLong(value, address);
	}

	template<>
	void writenum<complex>(complex value, uint32_t address)
	{
		memoryWriteLongLong(value, address);
	}

	template<>
	void writenum<float>(float value, uint32_t address)
	{
		static_assert(sizeof(value) == 4, "unexpected float size");

		memoryWriteLong(*((uint32_t *)&value), address);
	}

	template<>
	void writenum<double>(double value, uint32_t address)
	{
		static_assert(sizeof(value) == 8, "unexpected double size");

		memoryWriteLongLong(*((uint64_t *)&value), address);
	}

	template<>
	void writenum<long double>(long double value, uint32_t address)
	{
		static_assert(sizeof(value) == 16 || sizeof(value) == 12, "unexpected long double size");

		uint8_t buffer[16];

		std::memcpy(buffer, &value, sizeof(value));

		// copy 10 bytes over
		// little-endian specific.
		for(unsigned i = 0; i < 10; ++i)
			memoryWriteByte(buffer[9 - i], address + i);
	}

	decform decform::read(uint32_t address)
	{
		enum {
			_style = 0,
			_unused = 1,
			_digits = 2,
		};

		decform d;
		if (!address) return d;
		d.style = memoryReadByte(address + _style);
		d.digits = memoryReadWord(address + _digits);
		return d;
	}
	void decform::write(uint32_t address)
	{
		enum {
			_style = 0,
			_unused = 1,
			_digits = 2,
		};

		if (!address) return;
		memoryWriteByte(style, address + _style);
		memoryWriteWord(digits, address + _digits);
	}

	decimal decimal::read(uint32_t address)
	{
		enum {
			_sgn = 0,
			_exp = 2,
			_sig = 4,

			SIGDIGLEN = 20,
		};

		decimal d;
		if (!address) return d;

		d.sgn = memoryReadByte(address + _sgn);
		d.exp = (int16_t)memoryReadWord(address + _exp);
		//unsigned length = memoryReadByte(address + _sig);
		//length = std::min(length, (unsigned)SIGDIGLEN);
		d.sig = ToolBox::ReadPString(address + _sig, false);
		return d;
	}
	void decimal::write(uint32_t address)
	{
		enum {
			_sgn = 0,
			_exp = 2,
			_sig = 4,

			SIGDIGLEN = 20,
		};

		memoryWriteByte(sgn, address + _sgn);
		memoryWriteByte(0, address + _sgn + 1); // unused.
		memoryWriteWord(exp, address + _exp);

		// check if <= SIGDIGLEN?
		ToolBox::WritePString(address + _sig, sig);
	}

	void format_f(extended x, int precision, std::string &mm, std::string &nn)
	{
		char *buffer = nullptr;

		mm.clear();
		nn.clear();

		if (precision < 0) precision = 0;
		int length = asprintf(&buffer, "%.*Lf", precision, x);
		std::string tmp(buffer, length);
		free(buffer);

		auto dot = tmp.find('.');
		if (dot == tmp.npos)
		{
			mm = std::move(tmp);
		}
		else
		{
			mm = tmp.substr(0, dot);
			nn = tmp.substr(dot + 1);
		}

		// skip mm if it's 0
		if (mm.length() == 1 && mm.front() == '0') mm.clear();

		// skip nn if it's 0000...
		if (std::all_of(nn.begin(), nn.end(), [](char c){ return c == '0'; }))
			nn.clear();
	}

	void format_e(extended x, int precision, std::string &mm, std::string &nn, int &exp)
	{
		char *buffer = nullptr;

		exp = 0;
		mm.clear();
		nn.clear();

		if (precision < 0) precision = 0;
		if (precision > 19) precision = 19;

		int length = asprintf(&buffer, "%.*Le", precision, x);
		// output mm . nn e[+-]exp
		// mm e[+-]exp
		std::string tmp(buffer, length);
		free(buffer);

		auto dot = tmp.find('.');
		auto e = tmp.find('e');

		if (dot == tmp.npos)
		{
			mm = tmp.substr(0, e);
		}
		else
		{
			mm = tmp.substr(0, dot);
			nn = tmp.substr(dot + 1, e - dot - 1);
		}

		char sign = tmp[e+1];
		tmp = tmp.substr(e + 2);
		exp = std::stoi(tmp);
		if (sign == '-') exp = -exp;
	}

	uint16_t fx2dec()
	{
		// extended (80-bit fp) to decimal
		// convert a to d based on decform f
		// used by printf %g, %f, %e, etc


		uint16_t op;
		uint32_t f_adr;
		uint32_t a_adr;
		uint32_t d_adr;

		decform df;
		decimal d;

		StackFrame<14>(f_adr, a_adr, d_adr, op);


		Log("     FX2DEC(%08x, %08x, %08x, %04x)\n", f_adr, a_adr, d_adr, op);

		extended s = readnum<extended>(a_adr);
		df = decform::read(f_adr);

		if (ToolBox::Trace)
		{
			std::string tmp1 = std::to_string(s);
			Log("     %s (style: %d digits: %d)\n", tmp1.c_str(), df.style, df.digits);
		}


		/*
		 * SANE pp 30, 31
		 *
		 * Floating style:
		 * [-| ]m[.nnn]e[+|-]dddd
		 *
		 * Fixed style:
		 * [-]mmm[.nnn]
		 */


		if (df.digits < 0) df.digits = 0;
		if (df.digits > 19) df.digits = 19;

		fpinfo fpi(s);
		//fprintf(stderr, "%02x %02x %d %016llx\n", fpi.sign, fpi.one, fpi.exp, fpi.sig);


		d.sgn = signbit(s);

		// handle infinity, nan as a special case.
		switch (fpclassify(s))
		{
			case FP_ZERO:
				d.sig = "0";
				d.write(d_adr);
				return 0;

			case FP_NAN:
				// NAN type encoded in the sig.
				{
					char buffer[20]; // 16 + 2 needed
					snprintf(buffer, 20, "N%016llx", fpi.sig);
					d.sig = buffer;
					d.write(d_adr);
				}
				return 0;				

			case FP_INFINITE:

				d.sig = "I";
				d.write(d_adr);
				return 0;					

			default:
				break;

		}

		// normal and subnormal handled here....

		// float decimal: df.digits refers to the total length
		// fixed decimal: df.digits refers to the fractional part only.

		s = abs(s);


		if (s < 1.0 && df.style == decform::FLOATDECIMAL)
		{
			std::string mm;
			std::string nn;

			format_e(s, df.digits - 1, mm, nn, d.exp);

			d.sig = mm + nn;

			// better be < 0...
			if (d.exp < 0)
				d.exp -= nn.length();

			d.write(d_adr);
			return 0;
		}
		else // s > 1
		{

			std::string mm;
			std::string nn;

			format_f(s, df.digits, mm, nn);

			if (mm.empty() && nn.empty())
			{
				// very large 0.
				d.sig = "0";
				d.write(d_adr);
				return 0;
			}

			// if nn is empty (or 0s), this is a large number,
			// and we don't have to worry about the fraction.
			if (nn.empty())
			{
				d.exp = 0;

				if (df.style == decform::FIXEDDECIMAL) df.digits = 19;

				// limit the length.
				if (mm.length() > df.digits)
				{
					d.exp = mm.length() - df.digits;
					mm.resize(df.digits);
				}
				d.sig = std::move(mm);

			}
			else
			{
				if (df.style == decform::FIXEDDECIMAL)
				{
					// digits is the total size, mm + nn
					// re-format with new precision.
					// this is getting repetitive...

					if (mm.length())
					{
						int precision = df.digits - mm.length();
						if (precision < 0) precision = 1;	

						format_f(s, precision, mm, nn);					
					}
				}
				// todo -- if mm is empty and nn has leading 0s, 
				// drop the leading 0s and adjust the exponent
				// accordingly.

				d.sig = mm + nn;
				d.exp = -nn.length();

				if (d.sig.length() > 19)
				{
					d.exp += (d.sig.length() - 19);
					d.sig.resize(19);
				}
			}


			d.write(d_adr);
			return 0;
		}
	}


	template<class SrcType, class DestType = extended>
	uint16_t fadd(const char *name)
	{
		// faddi, etc.
		// destination is always extended.
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		StackFrame<10>(src, dest, op);

		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);
		DestType d = readnum<DestType>(dest);

		if (ToolBox::Trace)
		{
			std::string tmp1 = std::to_string(d);
			std::string tmp2 = std::to_string(s);
			Log("     %s + %s\n", tmp1.c_str(), tmp2.c_str());
		}

		d = d + s;

		writenum<DestType>(d, dest);
		return 0;
	}

	template<class SrcType, class DestType = extended>
	uint16_t fsub(const char *name)
	{
		// fsub, etc.
		// destination is always extended.
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		StackFrame<10>(src, dest, op);

		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);
		DestType d = readnum<DestType>(dest);

		if (ToolBox::Trace)
		{
			std::string tmp1 = std::to_string(d);
			std::string tmp2 = std::to_string(s);
			Log("     %s - %s\n", tmp1.c_str(), tmp2.c_str());
		}

		d = d - s;

		writenum<DestType>(d, dest);
		return 0;
	}

	template<class SrcType, class DestType = extended>
	uint16_t fmul(const char *name)
	{
		// multiply extended (80-bit fp)
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		StackFrame<10>(src, dest, op);

		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);
		DestType d = readnum<DestType>(dest);

		if (ToolBox::Trace)
		{
			std::string tmp1 = std::to_string(d);
			std::string tmp2 = std::to_string(s);
			Log("     %s * %s\n", tmp1.c_str(), tmp2.c_str());
		}

		d = d * s;

		writenum<DestType>((extended)d, dest);

		return 0;
	}

	template<class SrcType, class DestType = extended>
	uint16_t fdiv(const char *name)
	{
		// div extended (80-bit fp)
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		StackFrame<10>(src, dest, op);

		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);
		DestType d = readnum<DestType>(dest);

		if (ToolBox::Trace)
		{
			std::string tmp1 = std::to_string(d);
			std::string tmp2 = std::to_string(s);
			Log("     %s / %s\n", tmp1.c_str(), tmp2.c_str());
		}

		// dest = dest / src
		d = d / s;

		writenum<DestType>(d, dest);

		return 0;
	}


	template<class SrcType, class DestType>
	uint16_t fconvert(const char *name)
	{
		// type conversion.
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		StackFrame<10>(src, dest, op);

		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);

		if (ToolBox::Trace)
		{
			std::string tmp1 = to_string(s);
			Log("     %s\n", tmp1.c_str());
		}

		writenum<DestType>((DestType)s, dest);

		return 0;
	}

	extern "C" void cpuSetFlagsShift(BOOLE z, BOOLE n, BOOLE c, BOOLE v);
	template<class SrcType, class DestType = extended>
	uint16_t fcmp(const char *name)
	{
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		// TODO op & 0x0f == 0x08 vs 0x0a
		// for signaling unordered & NaN

		StackFrame<10>(src, dest, op);

		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);
		DestType d = readnum<DestType>(dest);

		if (ToolBox::Trace)
		{
			std::string tmp1 = std::to_string(d);
			std::string tmp2 = std::to_string(s);
			Log("     %s <> %s\n", tmp1.c_str(), tmp2.c_str());
		}

		// TODO -- verify if src/dest are backwards here
		//

		//
		// check if ordered...

		if (d > s)
		{
			cpuSetFlagsShift(false, false, false, false);
			return 0;
		}
		if (d < s)
		{
			cpuSetFlagsShift(false, true, true, false);
			return 0;
		}
		if (d == s)
		{
			cpuSetFlagsShift(true, false, false, false);
			return 0;
		}

		// unorderable?
		// signal?
		cpuSetFlagsShift(false, false, false, true);
		return 0;
	}

	template <class DestType>
	uint16_t fdecimal(const char *name)
	{
		uint16_t op;
		uint32_t decimalPtr;
		uint32_t dest;


		StackFrame<10>(decimalPtr, dest, op);

		uint16_t sgn = memoryReadByte(decimalPtr);
		int16_t exp = memoryReadWord(decimalPtr + 2);
		std::string sig;
		sig = ToolBox::ReadPString(decimalPtr + 4, false);

		Log("     %s({%c %s e%d}, %08x)\n",
			name,
			sgn ? '-' : ' ', sig.c_str(), exp,
			dest
		);

		extended tmp = 0;
		if (sig.length())
		{
			if (sig[0] == 'I')
			{
				tmp = INFINITY;
			}
			else if (sig[0] == 'N')
			{
				tmp = NAN; // todo -- nan type
			}
			else
			{
				tmp = stold(sig);

				while (exp > 0)
				{
					tmp = tmp * 10.0;
					exp--;
				}
				while (exp < 0)
				{
					tmp = tmp / 10.0;
					exp++;
				}
			}
		}
		if (sgn) tmp = -tmp;

		writenum<DestType>((DestType)tmp, dest);

		return 0;
	}



	template <class SrcType>
	uint16_t fclassify(const char *name)
	{
		/*
		 * The classify operations set the sign of the destination to
		 * the sign of the source and the value of the destination
		 * according to the class of the source, as shown in Table E-18.
		 * The destination is an integer variable. (pg 273)
		 *
		 *
		 * Table E-18
		 * Class Information
		 * ----------------------
		 * Class of SRC     Value
		 * ----------------------
		 * Signaling NaN    1
		 * Quiet NaN        2
		 * Infinity         3
		 * Zero             4
		 * Normalized       5
		 * Denormalized     6
		 *
		 * Table E-19
		 * ---------------------------
		 * Sign of SRC     Sign of DST
		 * ---------------------------
		 * Positive        Positive
		 * Negative        Negative
		 */

		// N.B. - Sane.h uses 0-5, but how can you have integer -0?
		uint16_t op;
		uint32_t dest;
		uint32_t src;

		StackFrame<10>(src, dest, op);
		Log("     %s(%08x, %08x, %04x)\n", name, src, dest, op);

		SrcType s = readnum<SrcType>(src);

		if (ToolBox::Trace)
		{
			std::string tmp1 = to_string(s);
			Log("     %s\n", tmp1.c_str());
		}


		int16_t klass = 0;

		switch(fpclassify(s))
		{
			case FP_INFINITE:
				klass = 3;
				break;
			case FP_NAN:
				// todo -- signaling NaN is indicated
				// by the MSB of the fraction field f
				// 1 is quiet, 0 is signaling.
				klass = 1;
				break;
			case FP_NORMAL:
				klass = 5;
				break;
			case FP_SUBNORMAL:
				klass = 6;
				break;
			case FP_ZERO:
				klass = 4;
				break;

		}
		if (signbit(s)) klass = -klass;

		if (dest) {
			memoryWriteWord(klass, dest);
		}
		return 0;
	}

	#pragma mark - environment

	/*
	 * environment is a uint16_t *.
	 * void setenvironment(environment e);
	 * void getenvironment(environment *e);
	 * void procentry(environment *e);
	 * void procexit(environment e);
	 */

	uint16_t fgetenv(void)
	{
		uint32_t address;
		uint16_t op;

		StackFrame<6>(address, op);
		Log("     FGETENV(%08x)\n", address);

		memoryWriteWord(Environment, address);
		return 0;
	}


	uint16_t fsetenv(void)
	{
		uint32_t address;
		uint16_t value;
		uint16_t op;

		StackFrame<6>(address, op);
		value = address ? memoryReadWord(address) : DefaultEnvironment;
		Log("     FSETENV(%08x (%04x))\n", address, value);

		Environment = value;
		return 0;
	}

	uint16_t fprocentry(void)
	{
		uint32_t address;
		uint16_t op;

		StackFrame<6>(address, op);

		Log("     FPROCENTRY(%08x)\n", address);

		if (address) memoryWriteWord(Environment, address);
		Environment = DefaultEnvironment;

		return 0;
	}

	uint16_t fprocexit(void)
	{
		uint32_t address;
		uint16_t value;
		uint16_t op;


		StackFrame<6>(address, op);
		value = address ? memoryReadWord(address) : DefaultEnvironment;
		Log("     FPROCEXIT(%08x (%04x))\n", address, value);

		// todo -- also should signal exceptions/halts at this point.
		Environment = value;
		return 0;
	}

	uint16_t ftintx()
	{
		// truncate (round towards 0 regardless of rounding settings)

		uint32_t address;
		uint16_t op;

		StackFrame<6>(address, op);

		Log("     FTINTX(%08x)\n", address);

		extended s = readnum<extended>(address);

		if (ToolBox::Trace)
		{
			std::string tmp1 = to_string(s);
			Log("     %s\n", tmp1.c_str());
		}
		s = std::trunc(s);
		writenum<extended>(s, address);
		return 0;
	}

	extern "C" void cpuSetFlagsAbs(UWO f);
	uint16_t fp68k(uint16_t trap)
	{
		uint16_t op;
		uint32_t sp;

		sp = cpuGetAReg(7);
		op = memoryReadWord(sp);

		Log("%04x FP68K(%04x)\n", trap, op);

		cpuSetFlagsAbs(0x4);

		if (op == 0x000b) return fx2dec();

		switch(op)
		{
			// addition
			case 0x0000: return fadd<extended>("FADDX");
			case 0x0800: return fadd<double>("FADDD");
			case 0x1000: return fadd<float>("FADDS");
			//case 0x3000: return fadd<complex>("FADDC");
			case 0x2000: return fadd<int16_t>("FADDI");
			case 0x2800: return fadd<int32_t>("FADDL");

			// subtraction
			case 0x0002: return fsub<extended>("FSUBX");
			case 0x0802: return fsub<double>("FSUBD");
			case 0x1002: return fsub<float>("FSUBS");
			//case 0x3002: return fsub<complex>("FSUBC");
			case 0x2002: return fsub<int16_t>("FSUBI");
			case 0x2802: return fsub<int32_t>("FSUBL");

			// multiplication
			case 0x0004: return fmul<extended>("FMULX");
			case 0x0804: return fmul<double>("FMULD");
			case 0x1004: return fmul<float>("FMULS");
			//case 0x3004: return fmul<complex>("FMUlC");
			case 0x2004: return fmul<int16_t>("FMULI");
			case 0x2804: return fmul<int32_t>("FMULL");

			// division
			case 0x0006: return fdiv<extended>("FDIVX");
			case 0x0806: return fdiv<double>("FDIVD");
			case 0x1006: return fdiv<float>("FDIVS");
			//case 0x3006: return fdiv<complex>("FDIVC");
			case 0x2006: return fdiv<int16_t>("FDIVI");
			case 0x2806: return fdiv<int32_t>("FDIVL");

			// comparison
			case 0x0008: return fcmp<extended>("FCMPX");
			case 0x0808: return fcmp<double>("FCMPD");
			case 0x1008: return fcmp<float>("FCMPS");
			//case 0x3008: return fcmp<complex>("FCMPC");
			case 0x2008: return fcmp<int16_t>("FCMPI");
			case 0x2808: return fcmp<int32_t>("FCMPL");

			case 0x000a: return fcmp<extended>("FCPXX");
			case 0x080a: return fcmp<double>("FCPXD");
			case 0x100a: return fcmp<float>("FCPXS");
			//case 0x300a: return fcmp<complex>("FCPXC");
			case 0x200a: return fcmp<int16_t>("FCPXI");
			case 0x280a: return fcmp<int32_t>("FCPXL");


			// conversion (extended -> ???)
			case 0x0010: return fconvert<extended, extended>("FX2X");
			case 0x0810: return fconvert<extended, double>("FX2D");
			case 0x1010: return fconvert<extended, float>("FX2S");
			case 0x3010: return fconvert<extended, complex>("FX2C");
			case 0x2010: return fconvert<extended, int16_t>("FX2I");
			case 0x2810: return fconvert<extended, int32_t>("FX2L");

			// conversion (??? -> extended)
			case 0x000e: return fconvert<extended, extended>("FX2X");
			case 0x080e: return fconvert<double, extended>("FD2X");
			case 0x100e: return fconvert<float, extended>("FS2X");
			case 0x300e: return fconvert<complex, extended>("FC2X");
			case 0x200e: return fconvert<int16_t, extended>("FI2X");
			case 0x280e: return fconvert<int32_t, extended>("FL2X");


			case 0x001c: return fclassify<extended>("FCLASSX");
			case 0x081c: return fclassify<double>("FCLASSD");
			case 0x101c: return fclassify<float>("FCLASSS");
			case 0x301c: return fclassify<complex>("FCLASSC");

			case 0x0009:
				// fdec2x
				return fdecimal<extended>("FDEC2X");
				break;

			case 0x0016: return ftintx();
			case 0x0017: return fprocentry();
			case 0x0019: return fprocexit();
			case 0x0003: return fgetenv();
			case 0x0001: return fsetenv();
		}


		fprintf(stderr, "fp68k -- op %04x is not yet supported\n", op);
		exit(1);

		return 0;
	}

	uint16_t NumToString(void)
	{
		/*
		 * on entry:
		 * A0 Pointer to pascal string
		 * D0 The number
		 *
		 * on exit:
		 * A0 Pointer to pascal string
		 * D0 Result code
		 *
		 */

		int32_t theNum = cpuGetDReg(0);
		uint32_t theString = cpuGetAReg(0);

		//std::string s = ToolBox::ReadPString(theString, false);
		Log("     NumToString(%08x, %08x)\n", theNum, theString);

		std::string s = std::to_string(theNum);

		ToolBox::WritePString(theString, s);

		return 0;
	}

	uint32_t StringToNum(void)
	{
		/*
		 * on entry:
		 * A0 Pointer to pascal string
		 *
		 * on exit:
		 * D0 the number
		 *
		 */

		uint32_t theString = cpuGetAReg(0);


		std::string s = ToolBox::ReadPString(theString, false);
		Log("     StringToNum(%s)\n", s.c_str());

		bool negative = false;
		uint32_t tmp = 0;

		if (!s.length()) return 0;

		auto iter = s.begin();

		// check for leading +-
		if (*iter == '-')
		{
			negative = true;
			++iter;
		}
		else if (*iter == '+')
		{
			negative = false;
			++iter;
		}

		for ( ; iter != s.end(); ++iter)
		{
			// doesn't actually check if it's a number.
			int value = *iter & 0x0f;
			tmp = tmp * 10 + value;
		}

		if (negative) tmp = -tmp;

		return tmp;
	}

	uint32_t fstr2dec(char type)
	{
		// void str2dec(const char *s,short *ix,decimal *d,short *vp);

#if 0
#define SIGDIGLEN 20						/* significant decimal digits */
#define DECSTROUTLEN 80 					/* max length for dec2str output */

struct decimal {
	char sgn;								/*sign 0 for +, 1 for -*/
	char unused;
	short exp;								/*decimal exponent*/
	struct{
		unsigned char length;
		unsigned char text[SIGDIGLEN];		/*significant digits */
		unsigned char unused;
		}sig;
};
#endif

		uint32_t stringPtr;
		uint32_t indexPtr;
		uint32_t decimalPtr;
		uint32_t validPtr;

		uint16_t valid;
		uint16_t index;
		decimal d;

		StackFrame<16>(stringPtr, indexPtr, decimalPtr, validPtr);

		index = memoryReadWord(indexPtr);

		std::string str;
		if (type == 'P') str = ToolBox::ReadPString(stringPtr, false);
		if (type == 'C') str = ToolBox::ReadCString(stringPtr, false);

		Log("     F%cSTR2DEC(%s, %04x, %08x, %08x)\n",
			 type, str.c_str(), index, decimalPtr, validPtr);

		if (type == 'P') index--;
		str2dec(str, index, d, valid);
		if (type == 'P') index++;

		memoryWriteWord(index, indexPtr);
		memoryWriteWord(valid, validPtr);

		if (d.sig.length() > 20)
		{
			// truncate and adjust the exponent
			// 1234e0 -> 123e1 -> 12e2 -> 1e3
			// 1234e-1 -> 123e-0 -> 12e1
			int over = d.sig.length() - 20;
			d.sig.resize(20);
			d.exp += over;
		}

		memoryWriteByte(d.sgn, decimalPtr);
		memoryWriteByte(0, decimalPtr + 1);
		memoryWriteWord(d.exp, decimalPtr + 2);
		ToolBox::WritePString(decimalPtr + 4, d.sig);

		return 0;
	}

	uint16_t fdec2str()
	{
		// void dec2str(const decform *f,const decimal *d,char *s);

		uint32_t f_adr;
		uint32_t d_adr;
		uint32_t s_adr;

		decform df;
		decimal d;

		StackFrame<12>(f_adr, d_adr, s_adr);


		Log("     FDEC2STR(%08x, %08x, %08x)\n", f_adr, d_adr, s_adr);

		df = decform::read(f_adr);
		d = decimal::read(d_adr);

		if (ToolBox::Trace)
		{
			Log("     %d %d %s\n", d.sgn, d.exp, d.sig.c_str());
			Log("     (style: %d digits: %d)\n", df.style, df.digits);
		}

		std::string s;

		if (df.digits < 0) df.digits = 0;
		if (d.sig.empty()) d.sig = "0";

		if (df.style == decform::FLOATDECIMAL)
		{
			// [-| m[.nnn]e[+|-]dddd

			// - or space.
			if (d.sgn) s.push_back('-');
			else s.push_back(' ');

			if (d.sig[0] == 'I')
			{
				s.append("INF");
				ToolBox::WritePString(s_adr, s);
				return 0;
			}
			if (d.sig[0] == 'N')
			{
				// todo -- include actual nan code.
				s.append("NAN(000)");
				ToolBox::WritePString(s_adr, s);
				return 0;	
			}

			// 1 leading digit.
			s.push_back(d.sig[0]);
			if (d.sig.length() > 1)
			{
				s.push_back('.');
				s.append(d.sig.substr(1));
			}
			s.push_back('e');
			if (d.exp < 0)
			{
				// to_string() will include the -
				s.append(std::to_string(d.exp));
			}
			else
			{
				s.push_back('+');
				s.append(std::to_string(d.exp));
			}


			ToolBox::WritePString(s_adr, s);
			return 0;
		}
		else
		{
			// [-] mmmm [. nnn]
			if (d.sgn) s.push_back('-');

			std::string mm;
			std::string nn;

			if (d.sig[0] == 'I')
			{
				s.append("INF");
				ToolBox::WritePString(s_adr, s);
				return 0;
			}
			if (d.sig[0] == 'N')
			{
				// todo -- include actual nan code.
				// check how SANE format it (hex/dec)
				s.append("NAN(000)");
				ToolBox::WritePString(s_adr, s);
				return 0;	
			}

			//
			std::string tmp = std::move(d.sig);
			if (d.exp >= 0)
			{
				// 0, 5 == 5
				// 1, 12 = 120

				mm = std::move(tmp);
				mm.append(d.exp, '0');
				tmp.clear();
			}
			else
			{
				// -1, 12 = 1.2
				// -2, 12 = 0.12
				// -3  12 = 0.012

				int m = tmp.length() + d.exp;
				if (m > 0)
				{
					mm = tmp.substr(0, m);
					tmp.erase(0, m);
					d.exp = 0;
				}
				else
				{
					mm = "0";
				}
			}

			s.append(mm);

			if (df.digits > 0)
			{
				s.push_back('.');

				// if negative exp, need to put in leading 0s. 
				// for a pathological case like -32768, this would
				// be silly.

				if (d.exp < 0)
					nn.append(-d.exp, '0');
				nn.append(tmp);
				nn.resize(df.digits, '0'); // todo -- should round...
				s.append(nn);
			}

			// if > 80 in length, return '?'
			if (s.length() > 80) s = "?";
			ToolBox::WritePString(s_adr, s);
			return 0;
		}


	}

	uint32_t decstr68k(uint16_t trap)
	{
		// this is a strange one since it may be sane or it may be the binary/decimal package.

		uint16_t op;

		StackFrame<2>(op);

		Log("%04x DECSTR68K(%04x)\n", trap, op);

		switch (op)
		{
		case 0x00:
			return NumToString();
			break;

		case 0x01:
			return StringToNum();
			break;

		case 0x02:
			// fpstr2dec
			return fstr2dec('P');
			break;

		case 0x03:
			// fdec2str
			return fdec2str();
			break;

		case 0x04:
			// fcstr2dec
			return fstr2dec('C');
			break;


		default:
			fprintf(stderr, "decstr68k -- op %04x is not yet supported\n", op);
			exit(1);
		}


		return 0;
	}


}