576 lines
11 KiB
C
576 lines
11 KiB
C
/*
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* /src/NTP/ntp-4/libntp/ieee754io.c,v 4.8 1999/02/21 12:17:36 kardel RELEASE_19990228_A
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*
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* $Created: Sun Jul 13 09:12:02 1997 $
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*
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* Copyright (C) 1997, 1998 by Frank Kardel
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdio.h>
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#include "l_stdlib.h"
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#include "ntp_stdlib.h"
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#include "ntp_fp.h"
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#include "ieee754io.h"
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static unsigned char get_byte P((unsigned char *, offsets_t, int *));
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#ifdef __not_yet__
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static void put_byte P((unsigned char *, offsets_t, int *, unsigned char));
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#endif
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#ifdef LIBDEBUG
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#include "lib_strbuf.h"
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static char *
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fmt_blong(
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unsigned long val,
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int cnt
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)
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{
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char *buf, *s;
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int i = cnt;
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val <<= 32 - cnt;
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LIB_GETBUF(buf);
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s = buf;
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while (i--)
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{
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if (val & 0x80000000)
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{
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*s++ = '1';
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}
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else
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{
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*s++ = '0';
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}
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val <<= 1;
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}
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*s = '\0';
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return buf;
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}
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static char *
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fmt_flt(
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unsigned int sign,
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unsigned long mh,
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unsigned long ml,
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unsigned long ch
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)
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{
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char *buf;
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LIB_GETBUF(buf);
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sprintf(buf, "%c %s %s %s", sign ? '-' : '+',
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fmt_blong(ch, 11),
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fmt_blong(mh, 20),
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fmt_blong(ml, 32));
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return buf;
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}
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static char *
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fmt_hex(
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unsigned char *bufp,
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int length
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)
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{
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char *buf;
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int i;
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LIB_GETBUF(buf);
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for (i = 0; i < length; i++)
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{
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sprintf(buf+i*2, "%02x", bufp[i]);
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}
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return buf;
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}
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#endif
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static unsigned char
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get_byte(
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unsigned char *bufp,
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offsets_t offset,
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int *fieldindex
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)
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{
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unsigned char val;
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val = *(bufp + offset[*fieldindex]);
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#ifdef LIBDEBUG
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if (debug > 4)
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printf("fetchieee754: getbyte(0x%08x, %d) = 0x%02x\n", (unsigned int)(bufp)+offset[*fieldindex], *fieldindex, val);
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#endif
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(*fieldindex)++;
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return val;
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}
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#ifdef __not_yet__
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static void
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put_byte(
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unsigned char *bufp,
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offsets_t offsets,
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int *fieldindex,
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unsigned char val
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)
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{
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*(bufp + offsets[*fieldindex]) = val;
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(*fieldindex)++;
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}
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#endif
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/*
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* make conversions to and from external IEEE754 formats and internal
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* NTP FP format.
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*/
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int
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fetch_ieee754(
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unsigned char **buffpp,
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int size,
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l_fp *lfpp,
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offsets_t offsets
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)
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{
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unsigned char *bufp = *buffpp;
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unsigned int sign;
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unsigned int bias;
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unsigned int maxexp;
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int mbits;
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u_long mantissa_low;
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u_long mantissa_high;
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u_long characteristic;
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long exponent;
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#ifdef LIBDEBUG
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int length;
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#endif
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unsigned char val;
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int fieldindex = 0;
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switch (size)
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{
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case IEEE_DOUBLE:
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#ifdef LIBDEBUG
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length = 8;
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#endif
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mbits = 52;
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bias = 1023;
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maxexp = 2047;
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break;
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case IEEE_SINGLE:
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#ifdef LIBDEBUG
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length = 4;
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#endif
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mbits = 23;
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bias = 127;
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maxexp = 255;
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break;
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default:
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return IEEE_BADCALL;
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}
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val = get_byte(bufp, offsets, &fieldindex); /* fetch sign byte & first part of characteristic */
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sign = (val & 0x80) != 0;
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characteristic = (val & 0x7F);
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val = get_byte(bufp, offsets, &fieldindex); /* fetch rest of characteristic and start of mantissa */
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switch (size)
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{
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case IEEE_SINGLE:
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characteristic <<= 1;
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characteristic |= (val & 0x80) != 0; /* grab last characteristic bit */
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mantissa_high = 0;
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mantissa_low = (val &0x7F) << 16;
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mantissa_low |= get_byte(bufp, offsets, &fieldindex) << 8;
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mantissa_low |= get_byte(bufp, offsets, &fieldindex);
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break;
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case IEEE_DOUBLE:
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characteristic <<= 4;
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characteristic |= (val & 0xF0) >> 4; /* grab lower characteristic bits */
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mantissa_high = (val & 0x0F) << 16;
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mantissa_high |= get_byte(bufp, offsets, &fieldindex) << 8;
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mantissa_high |= get_byte(bufp, offsets, &fieldindex);
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mantissa_low = get_byte(bufp, offsets, &fieldindex) << 24;
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mantissa_low |= get_byte(bufp, offsets, &fieldindex) << 16;
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mantissa_low |= get_byte(bufp, offsets, &fieldindex) << 8;
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mantissa_low |= get_byte(bufp, offsets, &fieldindex);
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break;
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default:
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return IEEE_BADCALL;
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}
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#ifdef LIBDEBUG
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if (debug > 4)
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{
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double d;
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float f;
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if (size == IEEE_SINGLE)
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{
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int i;
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for (i = 0; i < length; i++)
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{
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*((unsigned char *)(&f)+i) = *(*buffpp + offsets[i]);
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}
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d = f;
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}
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else
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{
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int i;
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for (i = 0; i < length; i++)
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{
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*((unsigned char *)(&d)+i) = *(*buffpp + offsets[i]);
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}
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}
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printf("fetchieee754: FP: %s -> %s -> %e(=%s)\n", fmt_hex(*buffpp, length),
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fmt_flt(sign, mantissa_high, mantissa_low, characteristic),
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d, fmt_hex((unsigned char *)&d, length));
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}
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#endif
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*buffpp += fieldindex;
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/*
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* detect funny numbers
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*/
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if (characteristic == maxexp)
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{
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/*
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* NaN or Infinity
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*/
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if (mantissa_low || mantissa_high)
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{
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/*
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* NaN
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*/
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return IEEE_NAN;
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}
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else
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{
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/*
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* +Inf or -Inf
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*/
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return sign ? IEEE_NEGINFINITY : IEEE_POSINFINITY;
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}
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}
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else
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{
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/*
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* collect real numbers
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*/
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L_CLR(lfpp);
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/*
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* check for overflows
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*/
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exponent = characteristic - bias;
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if (exponent > 31) /* sorry - hardcoded */
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{
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/*
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* overflow only in respect to NTP-FP representation
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*/
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return sign ? IEEE_NEGOVERFLOW : IEEE_POSOVERFLOW;
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}
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else
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{
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int frac_offset; /* where the fraction starts */
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frac_offset = mbits - exponent;
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if (characteristic == 0)
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{
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/*
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* de-normalized or tiny number - fits only as 0
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*/
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return IEEE_OK;
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}
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else
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{
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/*
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* adjust for implied 1
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*/
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if (mbits > 31)
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mantissa_high |= 1 << (mbits - 32);
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else
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mantissa_low |= 1 << mbits;
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/*
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* take mantissa apart - if only all machine would support
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* 64 bit operations 8-(
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*/
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if (frac_offset > mbits)
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{
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lfpp->l_ui = 0; /* only fractional number */
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frac_offset -= mbits + 1; /* will now contain right shift count - 1*/
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if (mbits > 31)
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{
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lfpp->l_uf = mantissa_high << (63 - mbits);
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lfpp->l_uf |= mantissa_low >> (mbits - 33);
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lfpp->l_uf >>= frac_offset;
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}
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else
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{
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lfpp->l_uf = mantissa_low >> frac_offset;
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}
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}
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else
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{
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if (frac_offset > 32)
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{
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/*
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* must split in high word
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*/
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lfpp->l_ui = mantissa_high >> (frac_offset - 32);
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lfpp->l_uf = (mantissa_high & ((1 << (frac_offset - 32)) - 1)) << (64 - frac_offset);
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lfpp->l_uf |= mantissa_low >> (frac_offset - 32);
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}
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else
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{
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/*
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* must split in low word
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*/
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lfpp->l_ui = mantissa_high << (32 - frac_offset);
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lfpp->l_ui |= (mantissa_low >> frac_offset) & ((1 << (32 - frac_offset)) - 1);
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lfpp->l_uf = (mantissa_low & ((1 << frac_offset) - 1)) << (32 - frac_offset);
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}
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}
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/*
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* adjust for sign
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*/
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if (sign)
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{
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L_NEG(lfpp);
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}
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return IEEE_OK;
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}
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}
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}
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}
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int
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put_ieee754(
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unsigned char **bufpp,
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int size,
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l_fp *lfpp,
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offsets_t offsets
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)
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{
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l_fp outlfp;
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#ifdef LIBDEBUG
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unsigned int sign;
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unsigned int bias;
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#endif
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/*unsigned int maxexp;*/
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int mbits;
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int msb;
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u_long mantissa_low = 0;
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u_long mantissa_high = 0;
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#ifdef LIBDEBUG
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u_long characteristic = 0;
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long exponent;
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#endif
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/*int length;*/
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unsigned long mask;
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outlfp = *lfpp;
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switch (size)
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{
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case IEEE_DOUBLE:
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/*length = 8;*/
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mbits = 52;
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#ifdef LIBDEBUG
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bias = 1023;
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#endif
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/*maxexp = 2047;*/
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break;
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case IEEE_SINGLE:
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/*length = 4;*/
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mbits = 23;
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#ifdef LIBDEBUG
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bias = 127;
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#endif
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/*maxexp = 255;*/
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break;
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default:
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return IEEE_BADCALL;
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}
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/*
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* find sign
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*/
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if (L_ISNEG(&outlfp))
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{
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L_NEG(&outlfp);
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#ifdef LIBDEBUG
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sign = 1;
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#endif
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}
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else
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{
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#ifdef LIBDEBUG
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sign = 0;
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#endif
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}
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if (L_ISZERO(&outlfp))
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{
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#ifdef LIBDEBUG
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exponent = mantissa_high = mantissa_low = 0; /* true zero */
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#endif
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}
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else
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{
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/*
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* find number of significant integer bits
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*/
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mask = 0x80000000;
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if (outlfp.l_ui)
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{
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msb = 63;
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while (mask && ((outlfp.l_ui & mask) == 0))
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{
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mask >>= 1;
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msb--;
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}
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}
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else
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{
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msb = 31;
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while (mask && ((outlfp.l_uf & mask) == 0))
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{
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mask >>= 1;
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msb--;
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}
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}
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switch (size)
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{
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case IEEE_SINGLE:
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mantissa_high = 0;
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if (msb >= 32)
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{
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mantissa_low = (outlfp.l_ui & ((1 << (msb - 32)) - 1)) << (mbits - (msb - 32));
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mantissa_low |= outlfp.l_uf >> (mbits - (msb - 32));
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}
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else
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{
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mantissa_low = (outlfp.l_uf << (mbits - msb)) & ((1 << mbits) - 1);
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}
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break;
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case IEEE_DOUBLE:
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if (msb >= 32)
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{
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mantissa_high = (outlfp.l_ui << (mbits - msb)) & ((1 << (mbits - 32)) - 1);
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mantissa_high |= outlfp.l_uf >> (32 - (mbits - msb));
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mantissa_low = (outlfp.l_ui & ((1 << (msb - mbits)) - 1)) << (32 - (msb - mbits));
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mantissa_low |= outlfp.l_uf >> (msb - mbits);
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}
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else
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{
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mantissa_high = outlfp.l_uf << (mbits - 32 - msb);
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mantissa_low = outlfp.l_uf << (mbits - 32);
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}
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}
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#ifdef LIBDEBUG
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exponent = msb - 32;
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characteristic = exponent + bias;
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if (debug > 4)
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printf("FP: %s\n", fmt_flt(sign, mantissa_high, mantissa_low, characteristic));
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#endif
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}
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return IEEE_OK;
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}
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#if defined(DEBUG) && defined(LIBDEBUG)
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int main(
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int argc,
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char **argv
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)
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{
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static offsets_t native_off = { 0, 1, 2, 3, 4, 5, 6, 7 };
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double f = 1.0;
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double *f_p = &f;
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l_fp fp;
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if (argc == 2)
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{
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if (sscanf(argv[1], "%lf", &f) != 1)
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{
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printf("cannot convert %s to a float\n", argv[1]);
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return 1;
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}
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}
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printf("double: %s %s\n", fmt_blong(*(unsigned long *)&f, 32), fmt_blong(*(unsigned long *)((char *)(&f)+4), 32));
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printf("fetch from %f = %d\n", f, fetch_ieee754((void *)&f_p, IEEE_DOUBLE, &fp, native_off));
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printf("fp [%s %s] = %s\n", fmt_blong(fp.l_ui, 32), fmt_blong(fp.l_uf, 32), mfptoa(fp.l_ui, fp.l_uf, 15));
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f_p = &f;
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put_ieee754((void *)&f_p, IEEE_DOUBLE, &fp, native_off);
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return 0;
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}
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#endif
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/*
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* ieee754io.c,v
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* Revision 4.8 1999/02/21 12:17:36 kardel
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* 4.91f reconcilation
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*
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* Revision 4.7 1999/02/21 11:26:03 kardel
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* renamed index to fieldindex to avoid index() name clash
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*
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* Revision 4.6 1998/11/15 20:27:52 kardel
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* Release 4.0.73e13 reconcilation
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*
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* Revision 4.5 1998/08/16 19:01:51 kardel
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* debug information only compile for LIBDEBUG case
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*
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* Revision 4.4 1998/08/09 09:39:28 kardel
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* Release 4.0.73e2 reconcilation
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*
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* Revision 4.3 1998/06/13 11:56:19 kardel
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* disabled putbute() for the time being
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*
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* Revision 4.2 1998/06/12 15:16:58 kardel
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* ansi2knr compatibility
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*
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* Revision 4.1 1998/05/24 07:59:56 kardel
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* conditional debug support
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*
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* Revision 4.0 1998/04/10 19:46:29 kardel
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* Start 4.0 release version numbering
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*
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* Revision 1.1 1998/04/10 19:27:46 kardel
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* initial NTP VERSION 4 integration of PARSE with GPS166 binary support
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*
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* Revision 1.1 1997/10/06 21:05:45 kardel
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* new parse structure
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*
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*/
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