450 lines
12 KiB
C
450 lines
12 KiB
C
/* atof_vax.c - turn a Flonum into a VAX floating point number
|
||
Copyright (C) 1987-2022 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 3, 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, 51 Franklin Street - Fifth Floor, Boston, MA
|
||
02110-1301, USA. */
|
||
|
||
#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
|
||
|
||
int flonum_gen2vax (int, FLONUM_TYPE *, LITTLENUM_TYPE *);
|
||
|
||
/* Number of chars in flonum type 'letter'. */
|
||
|
||
static unsigned int
|
||
atof_vax_sizeof (int 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;
|
||
}
|
||
|
||
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 (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 (LITTLENUM_TYPE *words)
|
||
{
|
||
*words = 0x8000; /* Floating Reserved Operand Code. */
|
||
}
|
||
|
||
|
||
static int /* 0 means letter is OK. */
|
||
what_kind_of_float (int 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;
|
||
|
||
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! */
|
||
|
||
static char *
|
||
atof_vax (char *str, /* Text to convert to binary. */
|
||
int 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 = 0;
|
||
f.sign = '\0';
|
||
|
||
if (what_kind_of_float (what_kind, &precision, &exponent_bits))
|
||
{
|
||
return_value = NULL;
|
||
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;
|
||
}
|
||
else if (flonum_gen2vax (what_kind, &f, words))
|
||
return_value = NULL;
|
||
}
|
||
|
||
return return_value;
|
||
}
|
||
|
||
/* In: a flonum, a vax floating point format.
|
||
Out: a vax floating-point bit pattern. */
|
||
|
||
int
|
||
flonum_gen2vax (int 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. */
|
||
|
||
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. */
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
return return_value;
|
||
}
|
||
|
||
/* JF this used to be in vax.c but this looks like a better place for it. */
|
||
|
||
/* 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 0.
|
||
Floating point literal.
|
||
Number of chars we used for the literal. */
|
||
|
||
#define MAXIMUM_NUMBER_OF_LITTLENUMS 8 /* For .hfloats. */
|
||
|
||
const char *
|
||
vax_md_atof (int what_statement_type,
|
||
char *literalP,
|
||
int *sizeP)
|
||
{
|
||
LITTLENUM_TYPE words[MAXIMUM_NUMBER_OF_LITTLENUMS];
|
||
char kind_of_float;
|
||
unsigned int number_of_chars;
|
||
LITTLENUM_TYPE *littlenumP;
|
||
|
||
switch (what_statement_type)
|
||
{
|
||
case 'F':
|
||
case 'f':
|
||
kind_of_float = 'f';
|
||
break;
|
||
|
||
case 'D':
|
||
case 'd':
|
||
kind_of_float = 'd';
|
||
break;
|
||
|
||
case 'g':
|
||
kind_of_float = 'g';
|
||
break;
|
||
|
||
case 'h':
|
||
kind_of_float = 'h';
|
||
break;
|
||
|
||
default:
|
||
kind_of_float = 0;
|
||
break;
|
||
};
|
||
|
||
if (kind_of_float)
|
||
{
|
||
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 (littlenumP = words; littlenumP < limit; littlenumP++)
|
||
{
|
||
md_number_to_chars (literalP, *littlenumP, sizeof (LITTLENUM_TYPE));
|
||
literalP += sizeof (LITTLENUM_TYPE);
|
||
};
|
||
}
|
||
else
|
||
number_of_chars = 0;
|
||
|
||
*sizeP = number_of_chars;
|
||
return kind_of_float ? NULL : _("Unrecognized or unsupported floating point constant");
|
||
}
|