/* file: pack_ieee_s.c */
/*
**
** COPYRIGHT (c) 1989 BY
** DIGITAL EQUIPMENT CORPORATION, MAYNARD, MASSACHUSETTS.
** ALL RIGHTS RESERVED.
**
** THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY BE USED AND COPIED
** ONLY IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE AND WITH THE
** INCLUSION OF THE ABOVE COPYRIGHT NOTICE. THIS SOFTWARE OR ANY OTHER
** COPIES THEREOF MAY NOT BE PROVIDED OR OTHERWISE MADE AVAILABLE TO ANY
** OTHER PERSON. NO TITLE TO AND OWNERSHIP OF THE SOFTWARE IS HEREBY
** TRANSFERRED.
**
** THE INFORMATION IN THIS SOFTWARE IS SUBJECT TO CHANGE WITHOUT NOTICE
** AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
** CORPORATION.
**
** DIGITAL ASSUMES NO RESPONSIBILITY FOR THE USE OR RELIABILITY OF ITS
** SOFTWARE ON EQUIPMENT WHICH IS NOT SUPPLIED BY DIGITAL.
**
*/
/*
**++
** Facility:
**
** CVT Run-Time Library
**
** Abstract:
**
** This module contains code to extract information from an
** UNPACKED_REAL structure and to create an IEEE single floating number
** with those bits.
**
** This module is meant to be used as an include file.
**
** Author: Math RTL
**
** Creation Date: November 24, 1989.
**
** Modification History:
**
**--
*/
/*
**++
** Functional Description:
**
** This module contains code to extract information from an
** UNPACKED_REAL structure and to create an IEEE single number
** with those bits.
**
** See the header files for a description of the UNPACKED_REAL
** structure.
**
** A normalized IEEE single precision floating number looks like:
**
** Sign bit, 8 exp bits (bias 127), 23 fraction bits
**
** 1.0 <= fraction < 2.0, MSB implicit
**
** For more details see "Mips R2000 Risc Architecture"
** by Gerry Kane, page 6-8 or ANSI/IEEE Std 754-1985.
**
**
** Implicit parameters:
**
** options: a word of flags, see include files.
**
** output_value: a pointer to the input parameter.
**
** r: an UNPACKED_REAL structure.
**
**--
*/
if (r[U_R_FLAGS] & U_R_UNUSUAL) {
if (r[U_R_FLAGS] & U_R_ZERO)
if (r[U_R_FLAGS] & U_R_NEGATIVE)
RpcpMemoryCopy(output_value, IEEE_S_NEG_ZERO, 4);
else
RpcpMemoryCopy(output_value, IEEE_S_POS_ZERO, 4);
else if (r[U_R_FLAGS] & U_R_INFINITY) {
if (r[U_R_FLAGS] & U_R_NEGATIVE)
RpcpMemoryCopy(output_value, IEEE_S_NEG_INFINITY, 4);
else
RpcpMemoryCopy(output_value, IEEE_S_POS_INFINITY, 4);
} else if (r[U_R_FLAGS] & U_R_INVALID) {
RpcpMemoryCopy(output_value, IEEE_S_INVALID, 4);
RAISE(cvt__invalid_value);
}
} else {
/* Precision varies if value will be a denorm */
/* So, figure out where to round (0 <= i <= 24). */
round_bit_position = r[U_R_EXP] - ((U_R_BIAS - 126) - 23);
if (round_bit_position < 0)
round_bit_position = 0;
else if (round_bit_position > 24)
round_bit_position = 24;
#include "round.c"
if (r[U_R_EXP] < (U_R_BIAS - 125)) {
/* Denorm or underflow */
if (r[U_R_EXP] < ((U_R_BIAS - 125) - 23)) {
/* Value is too small for a denorm, so underflow */
if (r[U_R_FLAGS] & U_R_NEGATIVE)
RpcpMemoryCopy(output_value, IEEE_S_NEG_ZERO, 4);
else
RpcpMemoryCopy(output_value, IEEE_S_POS_ZERO, 4);
if (options & CVT_C_ERR_UNDERFLOW) {
RAISE(cvt__underflow);
}
} else {
/* Figure leading zeros for denorm and right-justify fraction */
i = 32 - (r[U_R_EXP] - ((U_R_BIAS - 126) - 23));
r[1] >>= i;
/* Set sign bit */
r[1] |= (r[U_R_FLAGS] << 31);
if (options & CVT_C_BIG_ENDIAN) {
r[0] = ((r[1] << 24) | (r[1] >> 24));
r[0] |= ((r[1] << 8) & 0x00FF0000L);
r[0] |= ((r[1] >> 8) & 0x0000FF00L);
RpcpMemoryCopy(output_value, r, 4);
} else {
RpcpMemoryCopy(output_value, &r[1], 4);
}
}
} else if (r[U_R_EXP] > (U_R_BIAS + 128)) {
/* Overflow */
if (options & CVT_C_TRUNCATE) {
if (r[U_R_FLAGS] & U_R_NEGATIVE)
RpcpMemoryCopy(output_value, IEEE_S_NEG_HUGE, 4);
else
RpcpMemoryCopy(output_value, IEEE_S_POS_HUGE, 4);
} else if ((options & CVT_C_ROUND_TO_POS)
&& (r[U_R_FLAGS] & U_R_NEGATIVE)) {
RpcpMemoryCopy(output_value, IEEE_S_NEG_HUGE, 4);
} else if ((options & CVT_C_ROUND_TO_NEG)
&& !(r[U_R_FLAGS] & U_R_NEGATIVE)) {
RpcpMemoryCopy(output_value, IEEE_S_POS_HUGE, 4);
} else {
if (r[U_R_FLAGS] & U_R_NEGATIVE)
RpcpMemoryCopy(output_value, IEEE_S_NEG_INFINITY, 4);
else
RpcpMemoryCopy(output_value, IEEE_S_POS_INFINITY, 4);
}
RAISE(cvt__overflow);
} else {
/* Adjust bias of exponent */
r[U_R_EXP] -= (U_R_BIAS - 126);
/* Make room for exponent and sign bit */
r[1] >>= 8;
/* Clear implicit bit */
r[1] &= 0x007FFFFFL;
/* OR in exponent and sign bit */
r[1] |= (r[U_R_EXP] << 23);
r[1] |= (r[U_R_FLAGS] << 31);
if (options & CVT_C_BIG_ENDIAN) {
r[0] = ((r[1] << 24) | (r[1] >> 24));
r[0] |= ((r[1] << 8) & 0x00FF0000L);
r[0] |= ((r[1] >> 8) & 0x0000FF00L);
RpcpMemoryCopy(output_value, r, 4);
} else {
RpcpMemoryCopy(output_value, &r[1], 4);
}
}
}