/*	$OpenBSD: atof-vax.c,v 1.2 1998/02/15 18:49:11 niklas Exp $	*/

/* atof_vax.c - turn a Flonum into a VAX floating point number
   Copyright (C) 1987, 1992 Free Software Foundation, Inc.
   
   This file is part of GAS, the GNU Assembler.
   
   GAS is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
   
   GAS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with GAS; see the file COPYING.  If not, write to
   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* JF added these two for md_atof() */
#include "as.h"

/* Precision in LittleNums. */
#define MAX_PRECISION (8)
#define H_PRECISION (8)
#define G_PRECISION (4)
#define D_PRECISION (4)
#define F_PRECISION (2)

/* Length in LittleNums of guard bits. */
#define GUARD (2)

#if __STDC__ == 1

int flonum_gen2vax(int format_letter, FLONUM_TYPE *f, LITTLENUM_TYPE *words);

#else /* not __STDC__ */

int flonum_gen2vax();

#endif /* not __STDC__ */

int				/* Number of chars in flonum type 'letter'. */
    atof_vax_sizeof (letter)
char letter;
{
	int	return_value;
	
	/*
	 * Permitting uppercase letters is probably a bad idea.
	 * Please use only lower-cased letters in case the upper-cased
	 * ones become unsupported!
	 */
	switch (letter)
	    {
	    case 'f':
	    case 'F':
		    return_value = 4;
		    break;
		    
	    case 'd':
	    case 'D':
	    case 'g':
	    case 'G':
		    return_value = 8;
		    break;
		    
	    case 'h':
	    case 'H':
		    return_value = 16;
		    break;
		    
	    default:
		    return_value = 0;
		    break;
	    }
	return (return_value);
} /* atof_vax_sizeof */

static const long mask[] = {
	0x00000000,
	0x00000001,
	0x00000003,
	0x00000007,
	0x0000000f,
	0x0000001f,
	0x0000003f,
	0x0000007f,
	0x000000ff,
	0x000001ff,
	0x000003ff,
	0x000007ff,
	0x00000fff,
	0x00001fff,
	0x00003fff,
	0x00007fff,
	0x0000ffff,
	0x0001ffff,
	0x0003ffff,
	0x0007ffff,
	0x000fffff,
	0x001fffff,
	0x003fffff,
	0x007fffff,
	0x00ffffff,
	0x01ffffff,
	0x03ffffff,
	0x07ffffff,
	0x0fffffff,
	0x1fffffff,
	0x3fffffff,
	0x7fffffff,
	0xffffffff
    };


/* Shared between flonum_gen2vax and next_bits */
static int		bits_left_in_littlenum;
static LITTLENUM_TYPE *	littlenum_pointer;
static LITTLENUM_TYPE * littlenum_end;

static int
    next_bits (number_of_bits)
int		number_of_bits;
{
	int			return_value;
	
	if (littlenum_pointer<littlenum_end)
	    return 0;
	if (number_of_bits >= bits_left_in_littlenum)
	    {
		    return_value  = mask[bits_left_in_littlenum] & * littlenum_pointer;
		    number_of_bits -= bits_left_in_littlenum;
		    return_value <<= number_of_bits;
		    bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
		    littlenum_pointer --;
		    if (littlenum_pointer >= littlenum_end)
			return_value |= ( (* littlenum_pointer) >> (bits_left_in_littlenum) ) & mask[number_of_bits];
	    }
	else
	    {
		    bits_left_in_littlenum -= number_of_bits;
		    return_value = mask[number_of_bits] & ( (* littlenum_pointer) >> bits_left_in_littlenum);
	    }
	return (return_value);
}

static void
    make_invalid_floating_point_number (words)
LITTLENUM_TYPE *	words;
{
	* words = 0x8000;		/* Floating Reserved Operand Code */
}

static int			/* 0 means letter is OK. */
    what_kind_of_float (letter, precisionP, exponent_bitsP)
char		letter;	/* In: lowercase please. What kind of float? */
int *		precisionP; /* Number of 16-bit words in the float. */
long *		exponent_bitsP;	/* Number of exponent bits. */
{
	int	retval;			/* 0: OK. */
	
	retval = 0;
	switch (letter)
	    {
	    case 'f':
		    * precisionP = F_PRECISION;
		    * exponent_bitsP = 8;
		    break;
		    
	    case 'd':
		    * precisionP = D_PRECISION;
		    * exponent_bitsP = 8;
		    break;
		    
	    case 'g':
		    * precisionP = G_PRECISION;
		    * exponent_bitsP = 11;
		    break;
		    
	    case 'h':
		    * precisionP = H_PRECISION;
		    * exponent_bitsP = 15;
		    break;
		    
	    default:
		    retval = 69;
		    break;
	    }
	return (retval);
}

/***********************************************************************\
 *									*
 *	Warning: this returns 16-bit LITTLENUMs, because that is	*
 *	what the VAX thinks in. It is up to the caller to figure	*
 *	out any alignment problems and to conspire for the bytes/word	*
 *	to be emitted in the right order. Bigendians beware!		*
 *									*
 \***********************************************************************/

char * /* Return pointer past text consumed. */
    atof_vax(str, what_kind, words)
char *str; /* Text to convert to binary. */
char what_kind; /* 'd', 'f', 'g', 'h' */
LITTLENUM_TYPE *words; /* Build the binary here. */
{
	FLONUM_TYPE f;
	LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
	/* Extra bits for zeroed low-order bits. */
	/* The 1st MAX_PRECISION are zeroed, */
	/* the last contain flonum bits. */
	char *return_value;
	int precision; /* Number of 16-bit words in the format. */
	long exponent_bits;
	
	return_value = str;
	f.low = bits + MAX_PRECISION;
	f.high = NULL;
	f.leader = NULL;
	f.exponent = NULL;
	f.sign = '\0';
	
	if (what_kind_of_float (what_kind, & precision, & exponent_bits)) {
		return_value = NULL; /* We lost. */
		make_invalid_floating_point_number (words);
	}

	if (return_value) {
		memset(bits, '\0', sizeof(LITTLENUM_TYPE) * MAX_PRECISION);
		
		/* Use more LittleNums than seems */
		/* necessary: the highest flonum may have */
		/* 15 leading 0 bits, so could be useless. */
		f.high = f.low + precision - 1 + GUARD;
		
		if (atof_generic (& return_value, ".", "eE", & f)) {
			make_invalid_floating_point_number (words);
			return_value = NULL;	/* we lost */
		} else {
			if (flonum_gen2vax(what_kind, & f, words)) {
				return_value = NULL;
			}
		}
	}
	return(return_value);
} /* atof_vax() */

/*
 * In: a flonum, a vax floating point format.
 * Out: a vax floating-point bit pattern.
 */

int				/* 0: OK. */
    flonum_gen2vax (format_letter, f, words)
char format_letter; /* One of 'd' 'f' 'g' 'h'. */
FLONUM_TYPE *f;
LITTLENUM_TYPE *words;	/* Deliver answer here. */
{
	LITTLENUM_TYPE *lp;
	int precision;
	long exponent_bits;
	int return_value; /* 0 == OK. */
	
	return_value = what_kind_of_float(format_letter, &precision, &exponent_bits);
	
	if (return_value != 0) {
		make_invalid_floating_point_number (words);
	} else {
		if (f->low > f->leader) {
			/* 0.0e0 seen. */
memset(words, '\0', sizeof(LITTLENUM_TYPE) * precision);
		} else {
			long exponent_1;
			long exponent_2;
			long exponent_3;
			long exponent_4;
			int exponent_skippage;
			LITTLENUM_TYPE word1;
			
			/* JF: Deal with new Nan, +Inf and -Inf codes */
			if (f->sign != '-' && f->sign != '+') {
				make_invalid_floating_point_number(words);
				return return_value;
			}
			/*
			 * All vaxen floating_point formats (so far) have:
			 * Bit 15 is sign bit.
			 * Bits 14:n are excess-whatever exponent.
			 * Bits n-1:0 (if any) are most significant bits of fraction.
			 * Bits 15:0 of the next word are the next most significant bits.
			 * And so on for each other word.
			 *
			 * All this to be compatible with a KF11?? (Which is still faster
			 * than lots of vaxen I can think of, but it also has higher
			 * maintenance costs ... sigh).
			 *
			 * So we need: number of bits of exponent, number of bits of
			 * mantissa.
			 */
			
#ifdef NEVER  /******* This zeroing seems redundant - Dean 3may86 **********/
			/*
			 * No matter how few bits we got back from the atof()
			 * routine, add enough zero littlenums so the rest of the
			 * code won't run out of "significant" bits in the mantissa.
			 */
			{
				LITTLENUM_TYPE *ltp;
				for (ltp = f->leader + 1;
				     ltp <= f->low + precision;
				     ltp++) {
					*ltp = 0;
				}
			}
#endif
			
			bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
			littlenum_pointer = f->leader;
			littlenum_end = f->low;
			/* Seek (and forget) 1st significant bit */
			for (exponent_skippage = 0;
			     ! next_bits(1);
			     exponent_skippage ++) ;;
			
			exponent_1 = f->exponent + f->leader + 1 - f->low;
			/* Radix LITTLENUM_RADIX, point just higher than f->leader. */
			exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
			/* Radix 2. */
			exponent_3 = exponent_2 - exponent_skippage;
			/* Forget leading zeros, forget 1st bit. */
			exponent_4 = exponent_3 + (1 << (exponent_bits - 1));
			/* Offset exponent. */
			
			if (exponent_4 & ~mask[exponent_bits]) {
				/*
				 * Exponent overflow. Lose immediately.
				 */
				
				make_invalid_floating_point_number (words);
				
				/*
				 * We leave return_value alone: admit we read the
				 * number, but return a floating exception
				 * because we can't encode the number.
				 */
			} else {
				lp = words;
				
				/* Word 1. Sign, exponent and perhaps high bits. */
				/* Assume 2's complement integers. */
				word1 = (((exponent_4 &mask[exponent_bits]) << (15 - exponent_bits))
					 | ((f->sign == '+') ? 0 : 0x8000)
					 | next_bits(15 - exponent_bits));
				*lp++ = word1;
				
				/* The rest of the words are just mantissa bits. */
				for (; lp < words + precision; lp++) {
					*lp = next_bits(LITTLENUM_NUMBER_OF_BITS);
				}
				
				if (next_bits (1)) {
					/*
					 * Since the NEXT bit is a 1, round UP the mantissa.
					 * The cunning design of these hidden-1 floats permits
					 * us to let the mantissa overflow into the exponent, and
					 * it 'does the right thing'. However, we lose if the
					 * highest-order bit of the lowest-order word flips.
					 * Is that clear?
					 */
					
					unsigned long carry;
					
					/*
					  #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
					  Please allow at least 1 more bit in carry than is in a LITTLENUM.
					  We need that extra bit to hold a carry during a LITTLENUM carry
					  propagation. Another extra bit (kept 0) will assure us that we
					  don't get a sticky sign bit after shifting right, and that
					  permits us to propagate the carry without any masking of bits.
					  #endif
					  */
					for (carry = 1, lp--;
					     carry && (lp >= words);
					     lp--) {
						carry = *lp + carry;
						*lp = carry;
						carry >>= LITTLENUM_NUMBER_OF_BITS;
					}
					
					if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1))) {
						make_invalid_floating_point_number(words);
						/*
						 * We leave return_value alone: admit we read the
						 * number, but return a floating exception
						 * because we can't encode the number.
						 */
					}
				} /* if (we needed to round up) */
			} /* if (exponent overflow) */
		} /* if (0.0e0) */
	} /* if (float_type was OK) */
	return(return_value);
} /* flonum_gen2vax() */


/* JF this used to be in vax.c but this looks like a better place for it */

/*
 *		md_atof()
 *
 * In:	input_line_pointer->the 1st character of a floating-point
 *		number.
 *	1 letter denoting the type of statement that wants a
 *		binary floating point number returned.
 *	Address of where to build floating point literal.
 *		Assumed to be 'big enough'.
 *	Address of where to return size of literal (in chars).
 *
 * Out:	Input_line_pointer->of next char after floating number.
 *	Error message, or "".
 *	Floating point literal.
 *	Number of chars we used for the literal.
 */

#define MAXIMUM_NUMBER_OF_LITTLENUMS (8) /* For .hfloats. */

char *
    md_atof (what_statement_type, literalP, sizeP)
char	what_statement_type;
char *	literalP;
int *	sizeP;
{
	LITTLENUM_TYPE	words[MAXIMUM_NUMBER_OF_LITTLENUMS];
	register char		kind_of_float;
	register int		number_of_chars;
	register LITTLENUM_TYPE * littlenum_pointer;
	
	switch (what_statement_type)
	    {
	    case 'F':			/* .float */
	    case 'f':			/* .ffloat */
		    kind_of_float = 'f';
		    break;
		    
	    case 'D':			/* .double */
	    case 'd':			/* .dfloat */
		    kind_of_float = 'd';
		    break;
		    
	    case 'g':			/* .gfloat */
		    kind_of_float = 'g';
		    break;
		    
	    case 'h':			/* .hfloat */
		    kind_of_float = 'h';
		    break;
		    
	    default:
		    kind_of_float = 0;
		    break;
	    };
	
	if (kind_of_float)
	    {
		    register LITTLENUM_TYPE * limit;
		    
		    input_line_pointer = atof_vax (input_line_pointer,
						   kind_of_float,
						   words);
		    /*
		     * The atof_vax() builds up 16-bit numbers.
		     * Since the assembler may not be running on
		     * a little-endian machine, be very careful about
		     * converting words to chars.
		     */
		    number_of_chars = atof_vax_sizeof (kind_of_float);
		    know( number_of_chars <= MAXIMUM_NUMBER_OF_LITTLENUMS * sizeof(LITTLENUM_TYPE) );
		    limit = words + (number_of_chars / sizeof(LITTLENUM_TYPE));
		    for (littlenum_pointer = words;
			 littlenum_pointer < limit;
			 littlenum_pointer ++)
			{
				md_number_to_chars (literalP, * littlenum_pointer, sizeof(LITTLENUM_TYPE));
				literalP += sizeof(LITTLENUM_TYPE);
			};
	    }
	else
	    {
		    number_of_chars = 0;
	    };
	
	* sizeP = number_of_chars;
	return (kind_of_float ? "" : "Bad call to md_atof()");
}				/* md_atof() */

/* end of atof-vax.c */