1 |
#include "EXTERN.h" |
2 |
#include "perl.h" |
3 |
#include "XSUB.h" |
4 |
|
5 |
#include <string.h> |
6 |
|
7 |
// a compiler supporting C99 is required |
8 |
|
9 |
/* try to be compatible with older perls */ |
10 |
/* SvPV_nolen() macro first defined in 5.005_55 */ |
11 |
/* this is slow, not threadsafe, but works */ |
12 |
#include "patchlevel.h" |
13 |
#if (PATCHLEVEL == 4) || ((PATCHLEVEL == 5) && (SUBVERSION < 55)) |
14 |
static STRLEN nolen_na; |
15 |
# define SvPV_nolen(sv) SvPV ((sv), nolen_na) |
16 |
#endif |
17 |
#if PATCHLEVEL < 6 |
18 |
# define call_sv perl_call_sv |
19 |
#endif |
20 |
|
21 |
#define KEYLEN 8 // number of bytes in the l, m, r fields |
22 |
|
23 |
static SV * |
24 |
new_key (void) |
25 |
{ |
26 |
SV *new = NEWSV(0, KEYLEN); |
27 |
SvPOK_only (new); |
28 |
SvCUR_set (new, KEYLEN); |
29 |
|
30 |
return new; |
31 |
} |
32 |
|
33 |
MODULE = XML::DB PACKAGE = XML::DB::Key |
34 |
|
35 |
PROTOTYPES: ENABLE |
36 |
|
37 |
int |
38 |
KEYLEN() |
39 |
CODE: |
40 |
RETVAL = KEYLEN; |
41 |
OUTPUT: |
42 |
RETVAL |
43 |
|
44 |
SV * |
45 |
0() |
46 |
ALIAS: |
47 |
1 = 255 |
48 |
CODE: |
49 |
RETVAL = new_key (); |
50 |
memset (SvPVX (RETVAL), ix, KEYLEN); |
51 |
OUTPUT: |
52 |
RETVAL |
53 |
|
54 |
# calculcate l + r |
55 |
SV * |
56 |
m(ls,rs) |
57 |
SV * ls |
58 |
SV * rs |
59 |
CODE: |
60 |
unsigned char *l, *m, *r, *me; |
61 |
unsigned int mx, carry; |
62 |
|
63 |
RETVAL = new_key (); |
64 |
|
65 |
l = SvPVX (ls ) + KEYLEN; |
66 |
r = SvPVX (rs ) + KEYLEN; |
67 |
m = (me = SvPVX (RETVAL)) + KEYLEN; |
68 |
|
69 |
me [0] = 'U'; |
70 |
me [1] = 'U'; |
71 |
|
72 |
mx = (unsigned int)*--l + (unsigned int)*--r + 1; *--m = (mx & 0x0ff) >> 1; |
73 |
carry = mx & 0x100; |
74 |
|
75 |
do |
76 |
{ |
77 |
mx = (unsigned int)*--l + (unsigned int)*--r + (carry >> 8); *--m = (mx & 0x0ff) >> 1; |
78 |
|
79 |
m[1] |= (mx & 0x001) << 7; |
80 |
carry = (mx & 0x100); |
81 |
} |
82 |
while (me < m); |
83 |
|
84 |
m[0] |= carry >> 1; |
85 |
|
86 |
OUTPUT: |
87 |
RETVAL |
88 |
|
89 |
|