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#include "EXTERN.h" |
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#include "perl.h" |
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#include "XSUB.h" |
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|
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#include <string.h> |
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|
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// a compiler supporting C99 is required |
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|
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/* try to be compatible with older perls */ |
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/* SvPV_nolen() macro first defined in 5.005_55 */ |
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/* this is slow, not threadsafe, but works */ |
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#include "patchlevel.h" |
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#if (PATCHLEVEL == 4) || ((PATCHLEVEL == 5) && (SUBVERSION < 55)) |
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static STRLEN nolen_na; |
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# define SvPV_nolen(sv) SvPV ((sv), nolen_na) |
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#endif |
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#if PATCHLEVEL < 6 |
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# define call_sv perl_call_sv |
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#endif |
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|
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#define KEYLEN 8 // number of bytes in the l, m, r fields |
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|
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static SV * |
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new_key (void) |
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{ |
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SV *new = NEWSV(0, KEYLEN); |
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SvPOK_only (new); |
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SvCUR_set (new, KEYLEN); |
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|
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return new; |
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} |
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|
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MODULE = XML::DB PACKAGE = XML::DB::Key |
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|
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PROTOTYPES: ENABLE |
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|
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int |
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KEYLEN() |
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CODE: |
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RETVAL = KEYLEN; |
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OUTPUT: |
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RETVAL |
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|
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SV * |
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0() |
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ALIAS: |
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1 = 255 |
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CODE: |
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RETVAL = new_key (); |
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memset (SvPVX (RETVAL), ix, KEYLEN); |
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OUTPUT: |
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RETVAL |
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|
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# calculcate l + r |
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SV * |
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m(ls,rs) |
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SV * ls |
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SV * rs |
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CODE: |
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unsigned char *l, *m, *r, *me; |
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unsigned int mx, carry; |
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|
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RETVAL = new_key (); |
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|
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l = SvPVX (ls ) + KEYLEN; |
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r = SvPVX (rs ) + KEYLEN; |
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m = (me = SvPVX (RETVAL)) + KEYLEN; |
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|
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me [0] = 'U'; |
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me [1] = 'U'; |
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|
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mx = (unsigned int)*--l + (unsigned int)*--r + 1; *--m = (mx & 0x0ff) >> 1; |
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carry = mx & 0x100; |
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|
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do |
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{ |
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mx = (unsigned int)*--l + (unsigned int)*--r + (carry >> 8); *--m = (mx & 0x0ff) >> 1; |
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|
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m[1] |= (mx & 0x001) << 7; |
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carry = (mx & 0x100); |
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} |
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while (me < m); |
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|
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m[0] |= carry >> 1; |
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|
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OUTPUT: |
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RETVAL |
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|
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|
