1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/* prim2real.c - presentation element to real */
/*
* isode/psap/prim2real.c
*
* Contributed by Julian Onions, Nottingham University.
* July 1989 - this stuff is awful. If you're going to use it seriously then
* write a machine specific version rather than any attempt at portability.
*/
/*
* NOTICE
*
* Acquisition, use, and distribution of this module and related
* materials are subject to the restrictions of a license agreement.
* Consult the Preface in the User's Manual for the full terms of
* this agreement.
*
*/
/* LINTLIBRARY */
#include "psap.h"
/* */
static double decode_binary (), decode_decimal ();
double prim2real (pe)
register PE pe;
{
if (pe -> pe_form != PE_FORM_PRIM)
return pe_seterr (pe, PE_ERR_PRIM, NOTOK);
if (pe -> pe_len == 0)
return 0.0;
if (pe -> pe_prim == NULLPED)
return pe_seterr (pe, PE_ERR_PRIM, NOTOK);
if (pe -> pe_len > sizeof (double) + 1)
return pe_seterr (pe, PE_ERR_OVER, NOTOK);
pe -> pe_errno = PE_ERR_NONE; /* in case it's -1 */
if ((*(pe -> pe_prim) & 0x80) == 0x80)
return decode_binary (pe);
switch (*(pe -> pe_prim) & PE_REAL_FLAGS) {
case PE_REAL_DECENC:
return decode_decimal (pe);
case PE_REAL_SPECENC:
if (pe -> pe_len > 1)
return pe_seterr (pe, PE_ERR_OVER, NOTOK);
switch (*(pe -> pe_prim)) {
case PE_REAL_MINUSINF:
return HUGE;
case PE_REAL_PLUSINF:
return -HUGE;
default:
return pe_seterr (pe, PE_ERR_NOSUPP, NOTOK);
}
}
/* NOTREACHED */
}
/* */
static double decode_binary (pe)
PE pe;
{
int sign, base, factor;
int exponent, i;
double mantissa, di;
PElementData dp, ep;
dp = pe -> pe_prim;
sign = (*dp & PE_REAL_B_S) ? -1 : 1;
switch (*dp & PE_REAL_B_BASE) {
case PE_REAL_B_B2:
base = 2;
break;
case PE_REAL_B_B8:
base = 8;
break;
case PE_REAL_B_B16:
base = 16;
break;
default:
return pe_seterr(pe, PE_ERR_NOSUPP, NOTOK);
}
factor = ((int)(*dp & PE_REAL_B_F)) >> 2;
exponent = (dp[1] & 0x80) ? (-1) : 0;
switch (*dp++ & PE_REAL_B_EXP) {
case PE_REAL_B_EF3:
exponent = (exponent << 8) | (*dp++ & 0xff);
/* fall */
case PE_REAL_B_EF2:
exponent = (exponent << 8) | (*dp++ & 0xff);
/* fall */
case PE_REAL_B_EF1:
exponent = (exponent << 8) | (*dp++ & 0xff);
break;
case PE_REAL_B_EF4:
i = *dp++ & 0xff;
if (i > sizeof(int))
return pe_seterr (pe, PE_ERR_OVER, NOTOK);
for (; i > 0; i--)
exponent = (exponent << 8) | (*dp++ & 0xff);
break;
}
for (di = 0.0, ep = pe -> pe_prim + pe -> pe_len; dp < ep;) {
di *= 1 << 8; ;
di += (int)(*dp++ & 0xff);
}
mantissa = sign * di * (1 << factor);
return mantissa * pow ((double)base, (double)exponent);
}
/* */
static double decode_decimal (pe)
PE pe;
{
/* sorry - don't have the standard ! */
return pe_seterr (pe, PE_ERR_NOSUPP, NOTOK);
}
|
