-\f
-/* 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 "floatformat.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
-
-static unsigned long get_field PARAMS ((unsigned char *,
- enum floatformat_byteorders,
- unsigned int,
- unsigned int,
- unsigned int));
-
-/* 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 (data, order, total_len, start, len)
- unsigned char *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;
-
- /* Start at the least significant part of the field. */
- cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT;
- if (order == floatformat_little || order == floatformat_littlebyte_bigword)
- cur_byte = (total_len / FLOATFORMAT_CHAR_BIT) - cur_byte - 1;
- cur_bitshift =
- ((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT;
- result = *(data + cur_byte) >> (-cur_bitshift);
- cur_bitshift += FLOATFORMAT_CHAR_BIT;
- if (order == floatformat_little || order == floatformat_littlebyte_bigword)
- ++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; zero out the bits which are not part of
- this field. */
- result |=
- (*(data + cur_byte) & ((1 << (len - cur_bitshift)) - 1))
- << cur_bitshift;
- else
- result |= *(data + cur_byte) << cur_bitshift;
- cur_bitshift += FLOATFORMAT_CHAR_BIT;
- if (order == floatformat_little || order == floatformat_littlebyte_bigword)
- ++cur_byte;
- else
- --cur_byte;
- }
- return result;
-}
-
-/* Convert from FMT to a DOUBLEST.
- FROM is the address of the extended float.
- Store the DOUBLEST in *TO. */
-
-void
-floatformat_to_doublest (fmt, from, to)
- const struct floatformat *fmt;
- char *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 */
-
- /* If the mantissa bits are not contiguous from one end of the
- mantissa to the other, we need to make a private copy of the
- source bytes that is in the right order since the unpacking
- algorithm assumes that the bits are contiguous.
-
- Swap the bytes individually rather than accessing them through
- "long *" since we have no guarantee that they start on a long
- alignment, and also sizeof(long) for the host could be different
- than sizeof(long) for the target. FIXME: Assumes sizeof(long)
- for the target is 4. */
-
- if (fmt -> byteorder == floatformat_littlebyte_bigword)
- {
- static unsigned char *newfrom;
- unsigned char *swapin, *swapout;
- int longswaps;
-
- longswaps = fmt -> totalsize / FLOATFORMAT_CHAR_BIT;
- longswaps >>= 3;
-
- if (newfrom == NULL)
- {
- newfrom = xmalloc (fmt -> totalsize);
- }
- swapout = newfrom;
- swapin = ufrom;
- ufrom = newfrom;
- while (longswaps-- > 0)
- {
- /* This is ugly, but efficient */
- *swapout++ = swapin[4];
- *swapout++ = swapin[5];
- *swapout++ = swapin[6];
- *swapout++ = swapin[7];
- *swapout++ = swapin[0];
- *swapout++ = swapin[1];
- *swapout++ = swapin[2];
- *swapout++ = swapin[3];
- swapin += 8;
- }
- }
-
- exponent = get_field (ufrom, fmt->byteorder, 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 zero's, denorms or NaNs. */
- if (!special_exponent)
- exponent -= 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++;