fuchsia / third_party / binutils-gdb / 2588d938d15f72c6a80eb1152dd578469452c2fb / . / gdb / doublest.c

/* Floating point routines for GDB, the GNU debugger. | |

Copyright (C) 1986-2016 Free Software Foundation, Inc. | |

This file is part of GDB. | |

This program 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 of the License, or | |

(at your option) any later version. | |

This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */ | |

/* Support for converting target fp numbers into host DOUBLEST format. */ | |

/* XXX - This code should really be in libiberty/floatformat.c, | |

however configuration issues with libiberty made this very | |

difficult to do in the available time. */ | |

#include "defs.h" | |

#include "doublest.h" | |

#include "floatformat.h" | |

#include "gdbtypes.h" | |

#include <math.h> /* ldexp */ | |

/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not | |

going to bother with trying to muck around with whether it is defined in | |

a system header, what we do if not, etc. */ | |

#define FLOATFORMAT_CHAR_BIT 8 | |

/* The number of bytes that the largest floating-point type that we | |

can convert to doublest will need. */ | |

#define FLOATFORMAT_LARGEST_BYTES 16 | |

/* Extract a field which starts at START and is LEN bytes long. DATA and | |

TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ | |

static unsigned long | |

get_field (const bfd_byte *data, enum floatformat_byteorders order, | |

unsigned int total_len, unsigned int start, unsigned int len) | |

{ | |

unsigned long result; | |

unsigned int cur_byte; | |

int cur_bitshift; | |

/* Caller must byte-swap words before calling this routine. */ | |

gdb_assert (order == floatformat_little || order == floatformat_big); | |

/* Start at the least significant part of the field. */ | |

if (order == floatformat_little) | |

{ | |

/* We start counting from the other end (i.e, from the high bytes | |

rather than the low bytes). As such, we need to be concerned | |

with what happens if bit 0 doesn't start on a byte boundary. | |

I.e, we need to properly handle the case where total_len is | |

not evenly divisible by 8. So we compute ``excess'' which | |

represents the number of bits from the end of our starting | |

byte needed to get to bit 0. */ | |

int excess = FLOATFORMAT_CHAR_BIT - (total_len % FLOATFORMAT_CHAR_BIT); | |

cur_byte = (total_len / FLOATFORMAT_CHAR_BIT) | |

- ((start + len + excess) / FLOATFORMAT_CHAR_BIT); | |

cur_bitshift = ((start + len + excess) % FLOATFORMAT_CHAR_BIT) | |

- FLOATFORMAT_CHAR_BIT; | |

} | |

else | |

{ | |

cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT; | |

cur_bitshift = | |

((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT; | |

} | |

if (cur_bitshift > -FLOATFORMAT_CHAR_BIT) | |

result = *(data + cur_byte) >> (-cur_bitshift); | |

else | |

result = 0; | |

cur_bitshift += FLOATFORMAT_CHAR_BIT; | |

if (order == floatformat_little) | |

++cur_byte; | |

else | |

--cur_byte; | |

/* Move towards the most significant part of the field. */ | |

while (cur_bitshift < len) | |

{ | |

result |= (unsigned long)*(data + cur_byte) << cur_bitshift; | |

cur_bitshift += FLOATFORMAT_CHAR_BIT; | |

switch (order) | |

{ | |

case floatformat_little: | |

++cur_byte; | |

break; | |

case floatformat_big: | |

--cur_byte; | |

break; | |

} | |

} | |

if (len < sizeof(result) * FLOATFORMAT_CHAR_BIT) | |

/* Mask out bits which are not part of the field. */ | |

result &= ((1UL << len) - 1); | |

return result; | |

} | |

/* Normalize the byte order of FROM into TO. If no normalization is | |

needed then FMT->byteorder is returned and TO is not changed; | |

otherwise the format of the normalized form in TO is returned. */ | |

static enum floatformat_byteorders | |

floatformat_normalize_byteorder (const struct floatformat *fmt, | |

const void *from, void *to) | |

{ | |

const unsigned char *swapin; | |

unsigned char *swapout; | |

int words; | |

if (fmt->byteorder == floatformat_little | |

|| fmt->byteorder == floatformat_big) | |

return fmt->byteorder; | |

words = fmt->totalsize / FLOATFORMAT_CHAR_BIT; | |

words >>= 2; | |

swapout = (unsigned char *)to; | |

swapin = (const unsigned char *)from; | |

if (fmt->byteorder == floatformat_vax) | |

{ | |

while (words-- > 0) | |

{ | |

*swapout++ = swapin[1]; | |

*swapout++ = swapin[0]; | |

*swapout++ = swapin[3]; | |

*swapout++ = swapin[2]; | |

swapin += 4; | |

} | |

/* This may look weird, since VAX is little-endian, but it is | |

easier to translate to big-endian than to little-endian. */ | |

return floatformat_big; | |

} | |

else | |

{ | |

gdb_assert (fmt->byteorder == floatformat_littlebyte_bigword); | |

while (words-- > 0) | |

{ | |

*swapout++ = swapin[3]; | |

*swapout++ = swapin[2]; | |

*swapout++ = swapin[1]; | |

*swapout++ = swapin[0]; | |

swapin += 4; | |

} | |

return floatformat_big; | |

} | |

} | |

/* Convert from FMT to a DOUBLEST. | |

FROM is the address of the extended float. | |

Store the DOUBLEST in *TO. */ | |

static void | |

convert_floatformat_to_doublest (const struct floatformat *fmt, | |

const void *from, | |

DOUBLEST *to) | |

{ | |

unsigned char *ufrom = (unsigned char *) from; | |

DOUBLEST dto; | |

long exponent; | |

unsigned long mant; | |

unsigned int mant_bits, mant_off; | |

int mant_bits_left; | |

int special_exponent; /* It's a NaN, denorm or zero. */ | |

enum floatformat_byteorders order; | |

unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES]; | |

enum float_kind kind; | |

gdb_assert (fmt->totalsize | |

<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT); | |

/* For non-numbers, reuse libiberty's logic to find the correct | |

format. We do not lose any precision in this case by passing | |

through a double. */ | |

kind = floatformat_classify (fmt, (const bfd_byte *) from); | |

if (kind == float_infinite || kind == float_nan) | |

{ | |

double dto; | |

floatformat_to_double (fmt->split_half ? fmt->split_half : fmt, | |

from, &dto); | |

*to = (DOUBLEST) dto; | |

return; | |

} | |

order = floatformat_normalize_byteorder (fmt, ufrom, newfrom); | |

if (order != fmt->byteorder) | |

ufrom = newfrom; | |

if (fmt->split_half) | |

{ | |

DOUBLEST dtop, dbot; | |

floatformat_to_doublest (fmt->split_half, ufrom, &dtop); | |

/* Preserve the sign of 0, which is the sign of the top | |

half. */ | |

if (dtop == 0.0) | |

{ | |

*to = dtop; | |

return; | |

} | |

floatformat_to_doublest (fmt->split_half, | |

ufrom + fmt->totalsize / FLOATFORMAT_CHAR_BIT / 2, | |

&dbot); | |

*to = dtop + dbot; | |

return; | |

} | |

exponent = get_field (ufrom, order, fmt->totalsize, fmt->exp_start, | |

fmt->exp_len); | |

/* Note that if exponent indicates a NaN, we can't really do anything useful | |

(not knowing if the host has NaN's, or how to build one). So it will | |

end up as an infinity or something close; that is OK. */ | |

mant_bits_left = fmt->man_len; | |

mant_off = fmt->man_start; | |

dto = 0.0; | |

special_exponent = exponent == 0 || exponent == fmt->exp_nan; | |

/* Don't bias NaNs. Use minimum exponent for denorms. For | |

simplicity, we don't check for zero as the exponent doesn't matter. | |

Note the cast to int; exp_bias is unsigned, so it's important to | |

make sure the operation is done in signed arithmetic. */ | |

if (!special_exponent) | |

exponent -= fmt->exp_bias; | |

else if (exponent == 0) | |

exponent = 1 - fmt->exp_bias; | |

/* Build the result algebraically. Might go infinite, underflow, etc; | |

who cares. */ | |

/* If this format uses a hidden bit, explicitly add it in now. Otherwise, | |

increment the exponent by one to account for the integer bit. */ | |

if (!special_exponent) | |

{ | |

if (fmt->intbit == floatformat_intbit_no) | |

dto = ldexp (1.0, exponent); | |

else | |

exponent++; | |

} | |

while (mant_bits_left > 0) | |

{ | |

mant_bits = min (mant_bits_left, 32); | |

mant = get_field (ufrom, order, fmt->totalsize, mant_off, mant_bits); | |

dto += ldexp ((double) mant, exponent - mant_bits); | |

exponent -= mant_bits; | |

mant_off += mant_bits; | |

mant_bits_left -= mant_bits; | |

} | |

/* Negate it if negative. */ | |

if (get_field (ufrom, order, fmt->totalsize, fmt->sign_start, 1)) | |

dto = -dto; | |

*to = dto; | |

} | |

/* Set a field which starts at START and is LEN bytes long. DATA and | |

TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ | |

static void | |

put_field (unsigned char *data, enum floatformat_byteorders order, | |

unsigned int total_len, unsigned int start, unsigned int len, | |

unsigned long stuff_to_put) | |

{ | |

unsigned int cur_byte; | |

int cur_bitshift; | |

/* Caller must byte-swap words before calling this routine. */ | |

gdb_assert (order == floatformat_little || order == floatformat_big); | |

/* Start at the least significant part of the field. */ | |

if (order == floatformat_little) | |

{ | |

int excess = FLOATFORMAT_CHAR_BIT - (total_len % FLOATFORMAT_CHAR_BIT); | |

cur_byte = (total_len / FLOATFORMAT_CHAR_BIT) | |

- ((start + len + excess) / FLOATFORMAT_CHAR_BIT); | |

cur_bitshift = ((start + len + excess) % FLOATFORMAT_CHAR_BIT) | |

- FLOATFORMAT_CHAR_BIT; | |

} | |

else | |

{ | |

cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT; | |

cur_bitshift = | |

((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT; | |

} | |

if (cur_bitshift > -FLOATFORMAT_CHAR_BIT) | |

{ | |

*(data + cur_byte) &= | |

~(((1 << ((start + len) % FLOATFORMAT_CHAR_BIT)) - 1) | |

<< (-cur_bitshift)); | |

*(data + cur_byte) |= | |

(stuff_to_put & ((1 << FLOATFORMAT_CHAR_BIT) - 1)) << (-cur_bitshift); | |

} | |

cur_bitshift += FLOATFORMAT_CHAR_BIT; | |

if (order == floatformat_little) | |

++cur_byte; | |

else | |

--cur_byte; | |

/* Move towards the most significant part of the field. */ | |

while (cur_bitshift < len) | |

{ | |

if (len - cur_bitshift < FLOATFORMAT_CHAR_BIT) | |

{ | |

/* This is the last byte. */ | |

*(data + cur_byte) &= | |

~((1 << (len - cur_bitshift)) - 1); | |

*(data + cur_byte) |= (stuff_to_put >> cur_bitshift); | |

} | |

else | |

*(data + cur_byte) = ((stuff_to_put >> cur_bitshift) | |

& ((1 << FLOATFORMAT_CHAR_BIT) - 1)); | |

cur_bitshift += FLOATFORMAT_CHAR_BIT; | |

if (order == floatformat_little) | |

++cur_byte; | |

else | |

--cur_byte; | |

} | |

} | |

/* The converse: convert the DOUBLEST *FROM to an extended float and | |

store where TO points. Neither FROM nor TO have any alignment | |

restrictions. */ | |

static void | |

convert_doublest_to_floatformat (const struct floatformat *fmt, | |

const DOUBLEST *from, void *to) | |

{ | |

DOUBLEST dfrom; | |

int exponent; | |

DOUBLEST mant; | |

unsigned int mant_bits, mant_off; | |

int mant_bits_left; | |

unsigned char *uto = (unsigned char *) to; | |

enum floatformat_byteorders order = fmt->byteorder; | |

unsigned char newto[FLOATFORMAT_LARGEST_BYTES]; | |

if (order != floatformat_little) | |

order = floatformat_big; | |

if (order != fmt->byteorder) | |

uto = newto; | |

memcpy (&dfrom, from, sizeof (dfrom)); | |

memset (uto, 0, (fmt->totalsize + FLOATFORMAT_CHAR_BIT - 1) | |

/ FLOATFORMAT_CHAR_BIT); | |

if (fmt->split_half) | |

{ | |

/* Use static volatile to ensure that any excess precision is | |

removed via storing in memory, and so the top half really is | |

the result of converting to double. */ | |

static volatile double dtop, dbot; | |

DOUBLEST dtopnv, dbotnv; | |

dtop = (double) dfrom; | |

/* If the rounded top half is Inf, the bottom must be 0 not NaN | |

or Inf. */ | |

if (dtop + dtop == dtop && dtop != 0.0) | |

dbot = 0.0; | |

else | |

dbot = (double) (dfrom - (DOUBLEST) dtop); | |

dtopnv = dtop; | |

dbotnv = dbot; | |

floatformat_from_doublest (fmt->split_half, &dtopnv, uto); | |

floatformat_from_doublest (fmt->split_half, &dbotnv, | |

(uto | |

+ fmt->totalsize / FLOATFORMAT_CHAR_BIT / 2)); | |

return; | |

} | |

if (dfrom == 0) | |

return; /* Result is zero */ | |

if (dfrom != dfrom) /* Result is NaN */ | |

{ | |

/* From is NaN */ | |

put_field (uto, order, fmt->totalsize, fmt->exp_start, | |

fmt->exp_len, fmt->exp_nan); | |

/* Be sure it's not infinity, but NaN value is irrel. */ | |

put_field (uto, order, fmt->totalsize, fmt->man_start, | |

fmt->man_len, 1); | |

goto finalize_byteorder; | |

} | |

/* If negative, set the sign bit. */ | |

if (dfrom < 0) | |

{ | |

put_field (uto, order, fmt->totalsize, fmt->sign_start, 1, 1); | |

dfrom = -dfrom; | |

} | |

if (dfrom + dfrom == dfrom && dfrom != 0.0) /* Result is Infinity. */ | |

{ | |

/* Infinity exponent is same as NaN's. */ | |

put_field (uto, order, fmt->totalsize, fmt->exp_start, | |

fmt->exp_len, fmt->exp_nan); | |

/* Infinity mantissa is all zeroes. */ | |

put_field (uto, order, fmt->totalsize, fmt->man_start, | |

fmt->man_len, 0); | |

goto finalize_byteorder; | |

} | |

#ifdef HAVE_LONG_DOUBLE | |

mant = frexpl (dfrom, &exponent); | |

#else | |

mant = frexp (dfrom, &exponent); | |

#endif | |

if (exponent + fmt->exp_bias <= 0) | |

{ | |

/* The value is too small to be expressed in the destination | |

type (not enough bits in the exponent. Treat as 0. */ | |

put_field (uto, order, fmt->totalsize, fmt->exp_start, | |

fmt->exp_len, 0); | |

put_field (uto, order, fmt->totalsize, fmt->man_start, | |

fmt->man_len, 0); | |

goto finalize_byteorder; | |

} | |

if (exponent + fmt->exp_bias >= (1 << fmt->exp_len)) | |

{ | |

/* The value is too large to fit into the destination. | |

Treat as infinity. */ | |

put_field (uto, order, fmt->totalsize, fmt->exp_start, | |

fmt->exp_len, fmt->exp_nan); | |

put_field (uto, order, fmt->totalsize, fmt->man_start, | |

fmt->man_len, 0); | |

goto finalize_byteorder; | |

} | |

put_field (uto, order, fmt->totalsize, fmt->exp_start, fmt->exp_len, | |

exponent + fmt->exp_bias - 1); | |

mant_bits_left = fmt->man_len; | |

mant_off = fmt->man_start; | |

while (mant_bits_left > 0) | |

{ | |

unsigned long mant_long; | |

mant_bits = mant_bits_left < 32 ? mant_bits_left : 32; | |

mant *= 4294967296.0; | |

mant_long = ((unsigned long) mant) & 0xffffffffL; | |

mant -= mant_long; | |

/* If the integer bit is implicit, then we need to discard it. | |

If we are discarding a zero, we should be (but are not) creating | |

a denormalized number which means adjusting the exponent | |

(I think). */ | |

if (mant_bits_left == fmt->man_len | |

&& fmt->intbit == floatformat_intbit_no) | |

{ | |

mant_long <<= 1; | |

mant_long &= 0xffffffffL; | |

/* If we are processing the top 32 mantissa bits of a doublest | |

so as to convert to a float value with implied integer bit, | |

we will only be putting 31 of those 32 bits into the | |

final value due to the discarding of the top bit. In the | |

case of a small float value where the number of mantissa | |

bits is less than 32, discarding the top bit does not alter | |

the number of bits we will be adding to the result. */ | |

if (mant_bits == 32) | |

mant_bits -= 1; | |

} | |

if (mant_bits < 32) | |

{ | |

/* The bits we want are in the most significant MANT_BITS bits of | |

mant_long. Move them to the least significant. */ | |

mant_long >>= 32 - mant_bits; | |

} | |

put_field (uto, order, fmt->totalsize, | |

mant_off, mant_bits, mant_long); | |

mant_off += mant_bits; | |

mant_bits_left -= mant_bits; | |

} | |

finalize_byteorder: | |

/* Do we need to byte-swap the words in the result? */ | |

if (order != fmt->byteorder) | |

floatformat_normalize_byteorder (fmt, newto, to); | |

} | |

/* Check if VAL (which is assumed to be a floating point number whose | |

format is described by FMT) is negative. */ | |

int | |

floatformat_is_negative (const struct floatformat *fmt, | |

const bfd_byte *uval) | |

{ | |

enum floatformat_byteorders order; | |

unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES]; | |

gdb_assert (fmt != NULL); | |

gdb_assert (fmt->totalsize | |

<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT); | |

/* An IBM long double (a two element array of double) always takes the | |

sign of the first double. */ | |

if (fmt->split_half) | |

fmt = fmt->split_half; | |

order = floatformat_normalize_byteorder (fmt, uval, newfrom); | |

if (order != fmt->byteorder) | |

uval = newfrom; | |

return get_field (uval, order, fmt->totalsize, fmt->sign_start, 1); | |

} | |

/* Check if VAL is "not a number" (NaN) for FMT. */ | |

enum float_kind | |

floatformat_classify (const struct floatformat *fmt, | |

const bfd_byte *uval) | |

{ | |

long exponent; | |

unsigned long mant; | |

unsigned int mant_bits, mant_off; | |

int mant_bits_left; | |

enum floatformat_byteorders order; | |

unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES]; | |

int mant_zero; | |

gdb_assert (fmt != NULL); | |

gdb_assert (fmt->totalsize | |

<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT); | |

/* An IBM long double (a two element array of double) can be classified | |

by looking at the first double. inf and nan are specified as | |

ignoring the second double. zero and subnormal will always have | |

the second double 0.0 if the long double is correctly rounded. */ | |

if (fmt->split_half) | |

fmt = fmt->split_half; | |

order = floatformat_normalize_byteorder (fmt, uval, newfrom); | |

if (order != fmt->byteorder) | |

uval = newfrom; | |

exponent = get_field (uval, order, fmt->totalsize, fmt->exp_start, | |

fmt->exp_len); | |

mant_bits_left = fmt->man_len; | |

mant_off = fmt->man_start; | |

mant_zero = 1; | |

while (mant_bits_left > 0) | |

{ | |

mant_bits = min (mant_bits_left, 32); | |

mant = get_field (uval, order, fmt->totalsize, mant_off, mant_bits); | |

/* If there is an explicit integer bit, mask it off. */ | |

if (mant_off == fmt->man_start | |

&& fmt->intbit == floatformat_intbit_yes) | |

mant &= ~(1 << (mant_bits - 1)); | |

if (mant) | |

{ | |

mant_zero = 0; | |

break; | |

} | |

mant_off += mant_bits; | |

mant_bits_left -= mant_bits; | |

} | |

/* If exp_nan is not set, assume that inf, NaN, and subnormals are not | |

supported. */ | |

if (! fmt->exp_nan) | |

{ | |

if (mant_zero) | |

return float_zero; | |

else | |

return float_normal; | |

} | |

if (exponent == 0 && !mant_zero) | |

return float_subnormal; | |

if (exponent == fmt->exp_nan) | |

{ | |

if (mant_zero) | |

return float_infinite; | |

else | |

return float_nan; | |

} | |

if (mant_zero) | |

return float_zero; | |

return float_normal; | |

} | |

/* Convert the mantissa of VAL (which is assumed to be a floating | |

point number whose format is described by FMT) into a hexadecimal | |

and store it in a static string. Return a pointer to that string. */ | |

const char * | |

floatformat_mantissa (const struct floatformat *fmt, | |

const bfd_byte *val) | |

{ | |

unsigned char *uval = (unsigned char *) val; | |

unsigned long mant; | |

unsigned int mant_bits, mant_off; | |

int mant_bits_left; | |

static char res[50]; | |

char buf[9]; | |

int len; | |

enum floatformat_byteorders order; | |

unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES]; | |

gdb_assert (fmt != NULL); | |

gdb_assert (fmt->totalsize | |

<= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT); | |

/* For IBM long double (a two element array of double), return the | |

mantissa of the first double. The problem with returning the | |

actual mantissa from both doubles is that there can be an | |

arbitrary number of implied 0's or 1's between the mantissas | |

of the first and second double. In any case, this function | |

is only used for dumping out nans, and a nan is specified to | |

ignore the value in the second double. */ | |

if (fmt->split_half) | |

fmt = fmt->split_half; | |

order = floatformat_normalize_byteorder (fmt, uval, newfrom); | |

if (order != fmt->byteorder) | |

uval = newfrom; | |

if (! fmt->exp_nan) | |

return 0; | |

/* Make sure we have enough room to store the mantissa. */ | |

gdb_assert (sizeof res > ((fmt->man_len + 7) / 8) * 2); | |

mant_off = fmt->man_start; | |

mant_bits_left = fmt->man_len; | |

mant_bits = (mant_bits_left % 32) > 0 ? mant_bits_left % 32 : 32; | |

mant = get_field (uval, order, fmt->totalsize, mant_off, mant_bits); | |

len = xsnprintf (res, sizeof res, "%lx", mant); | |

mant_off += mant_bits; | |

mant_bits_left -= mant_bits; | |

while (mant_bits_left > 0) | |

{ | |

mant = get_field (uval, order, fmt->totalsize, mant_off, 32); | |

xsnprintf (buf, sizeof buf, "%08lx", mant); | |

gdb_assert (len + strlen (buf) <= sizeof res); | |

strcat (res, buf); | |

mant_off += 32; | |

mant_bits_left -= 32; | |

} | |

return res; | |

} | |

/* Convert TO/FROM target to the hosts DOUBLEST floating-point format. | |

If the host and target formats agree, we just copy the raw data | |

into the appropriate type of variable and return, letting the host | |

increase precision as necessary. Otherwise, we call the conversion | |

routine and let it do the dirty work. Note that even if the target | |

and host floating-point formats match, the length of the types | |

might still be different, so the conversion routines must make sure | |

to not overrun any buffers. For example, on x86, long double is | |

the 80-bit extended precision type on both 32-bit and 64-bit ABIs, | |

but by default it is stored as 12 bytes on 32-bit, and 16 bytes on | |

64-bit, for alignment reasons. See comment in store_typed_floating | |

for a discussion about zeroing out remaining bytes in the target | |

buffer. */ | |

static const struct floatformat *host_float_format = GDB_HOST_FLOAT_FORMAT; | |

static const struct floatformat *host_double_format = GDB_HOST_DOUBLE_FORMAT; | |

static const struct floatformat *host_long_double_format | |

= GDB_HOST_LONG_DOUBLE_FORMAT; | |

/* See doublest.h. */ | |

size_t | |

floatformat_totalsize_bytes (const struct floatformat *fmt) | |

{ | |

return ((fmt->totalsize + FLOATFORMAT_CHAR_BIT - 1) | |

/ FLOATFORMAT_CHAR_BIT); | |

} | |

void | |

floatformat_to_doublest (const struct floatformat *fmt, | |

const void *in, DOUBLEST *out) | |

{ | |

gdb_assert (fmt != NULL); | |

if (fmt == host_float_format) | |

{ | |

float val = 0; | |

memcpy (&val, in, floatformat_totalsize_bytes (fmt)); | |

*out = val; | |

} | |

else if (fmt == host_double_format) | |

{ | |

double val = 0; | |

memcpy (&val, in, floatformat_totalsize_bytes (fmt)); | |

*out = val; | |

} | |

else if (fmt == host_long_double_format) | |

{ | |

long double val = 0; | |

memcpy (&val, in, floatformat_totalsize_bytes (fmt)); | |

*out = val; | |

} | |

else | |

convert_floatformat_to_doublest (fmt, in, out); | |

} | |

void | |

floatformat_from_doublest (const struct floatformat *fmt, | |

const DOUBLEST *in, void *out) | |

{ | |

gdb_assert (fmt != NULL); | |

if (fmt == host_float_format) | |

{ | |

float val = *in; | |

memcpy (out, &val, floatformat_totalsize_bytes (fmt)); | |

} | |

else if (fmt == host_double_format) | |

{ | |

double val = *in; | |

memcpy (out, &val, floatformat_totalsize_bytes (fmt)); | |

} | |

else if (fmt == host_long_double_format) | |

{ | |

long double val = *in; | |

memcpy (out, &val, floatformat_totalsize_bytes (fmt)); | |

} | |

else | |

convert_doublest_to_floatformat (fmt, in, out); | |

} | |

/* Return a floating-point format for a floating-point variable of | |

length LEN. If no suitable floating-point format is found, an | |

error is thrown. | |

We need this functionality since information about the | |

floating-point format of a type is not always available to GDB; the | |

debug information typically only tells us the size of a | |

floating-point type. | |

FIXME: kettenis/2001-10-28: In many places, particularly in | |

target-dependent code, the format of floating-point types is known, | |

but not passed on by GDB. This should be fixed. */ | |

static const struct floatformat * | |

floatformat_from_length (struct gdbarch *gdbarch, int len) | |

{ | |

const struct floatformat *format; | |

if (len * TARGET_CHAR_BIT == gdbarch_half_bit (gdbarch)) | |

format = gdbarch_half_format (gdbarch) | |

[gdbarch_byte_order (gdbarch)]; | |

else if (len * TARGET_CHAR_BIT == gdbarch_float_bit (gdbarch)) | |

format = gdbarch_float_format (gdbarch) | |

[gdbarch_byte_order (gdbarch)]; | |

else if (len * TARGET_CHAR_BIT == gdbarch_double_bit (gdbarch)) | |

format = gdbarch_double_format (gdbarch) | |

[gdbarch_byte_order (gdbarch)]; | |

else if (len * TARGET_CHAR_BIT == gdbarch_long_double_bit (gdbarch)) | |

format = gdbarch_long_double_format (gdbarch) | |

[gdbarch_byte_order (gdbarch)]; | |

/* On i386 the 'long double' type takes 96 bits, | |

while the real number of used bits is only 80, | |

both in processor and in memory. | |

The code below accepts the real bit size. */ | |

else if ((gdbarch_long_double_format (gdbarch) != NULL) | |

&& (len * TARGET_CHAR_BIT | |

== gdbarch_long_double_format (gdbarch)[0]->totalsize)) | |

format = gdbarch_long_double_format (gdbarch) | |

[gdbarch_byte_order (gdbarch)]; | |

else | |

format = NULL; | |

if (format == NULL) | |

error (_("Unrecognized %d-bit floating-point type."), | |

len * TARGET_CHAR_BIT); | |

return format; | |

} | |

const struct floatformat * | |

floatformat_from_type (const struct type *type) | |

{ | |

struct gdbarch *gdbarch = get_type_arch (type); | |

const struct floatformat *fmt; | |

gdb_assert (TYPE_CODE (type) == TYPE_CODE_FLT); | |

if (TYPE_FLOATFORMAT (type) != NULL) | |

fmt = TYPE_FLOATFORMAT (type)[gdbarch_byte_order (gdbarch)]; | |

else | |

fmt = floatformat_from_length (gdbarch, TYPE_LENGTH (type)); | |

gdb_assert (TYPE_LENGTH (type) >= floatformat_totalsize_bytes (fmt)); | |

return fmt; | |

} | |

/* Extract a floating-point number of type TYPE from a target-order | |

byte-stream at ADDR. Returns the value as type DOUBLEST. */ | |

DOUBLEST | |

extract_typed_floating (const void *addr, const struct type *type) | |

{ | |

const struct floatformat *fmt = floatformat_from_type (type); | |

DOUBLEST retval; | |

floatformat_to_doublest (fmt, addr, &retval); | |

return retval; | |

} | |

/* Store VAL as a floating-point number of type TYPE to a target-order | |

byte-stream at ADDR. */ | |

void | |

store_typed_floating (void *addr, const struct type *type, DOUBLEST val) | |

{ | |

const struct floatformat *fmt = floatformat_from_type (type); | |

/* FIXME: kettenis/2001-10-28: It is debatable whether we should | |

zero out any remaining bytes in the target buffer when TYPE is | |

longer than the actual underlying floating-point format. Perhaps | |

we should store a fixed bitpattern in those remaining bytes, | |

instead of zero, or perhaps we shouldn't touch those remaining | |

bytes at all. | |

NOTE: cagney/2001-10-28: With the way things currently work, it | |

isn't a good idea to leave the end bits undefined. This is | |

because GDB writes out the entire sizeof(<floating>) bits of the | |

floating-point type even though the value might only be stored | |

in, and the target processor may only refer to, the first N < | |

TYPE_LENGTH (type) bits. If the end of the buffer wasn't | |

initialized, GDB would write undefined data to the target. An | |

errant program, refering to that undefined data, would then | |

become non-deterministic. | |

See also the function convert_typed_floating below. */ | |

memset (addr, 0, TYPE_LENGTH (type)); | |

floatformat_from_doublest (fmt, &val, addr); | |

} | |

/* Convert a floating-point number of type FROM_TYPE from a | |

target-order byte-stream at FROM to a floating-point number of type | |

TO_TYPE, and store it to a target-order byte-stream at TO. */ | |

void | |

convert_typed_floating (const void *from, const struct type *from_type, | |

void *to, const struct type *to_type) | |

{ | |

const struct floatformat *from_fmt = floatformat_from_type (from_type); | |

const struct floatformat *to_fmt = floatformat_from_type (to_type); | |

if (from_fmt == NULL || to_fmt == NULL) | |

{ | |

/* If we don't know the floating-point format of FROM_TYPE or | |

TO_TYPE, there's not much we can do. We might make the | |

assumption that if the length of FROM_TYPE and TO_TYPE match, | |

their floating-point format would match too, but that | |

assumption might be wrong on targets that support | |

floating-point types that only differ in endianness for | |

example. So we warn instead, and zero out the target buffer. */ | |

warning (_("Can't convert floating-point number to desired type.")); | |

memset (to, 0, TYPE_LENGTH (to_type)); | |

} | |

else if (from_fmt == to_fmt) | |

{ | |

/* We're in business. The floating-point format of FROM_TYPE | |

and TO_TYPE match. However, even though the floating-point | |

format matches, the length of the type might still be | |

different. Make sure we don't overrun any buffers. See | |

comment in store_typed_floating for a discussion about | |

zeroing out remaining bytes in the target buffer. */ | |

memset (to, 0, TYPE_LENGTH (to_type)); | |

memcpy (to, from, min (TYPE_LENGTH (from_type), TYPE_LENGTH (to_type))); | |

} | |

else | |

{ | |

/* The floating-point types don't match. The best we can do | |

(apart from simulating the target FPU) is converting to the | |

widest floating-point type supported by the host, and then | |

again to the desired type. */ | |

DOUBLEST d; | |

floatformat_to_doublest (from_fmt, from, &d); | |

floatformat_from_doublest (to_fmt, &d, to); | |

} | |

} |