strw_instrrev.c

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/* instrrevw function */

#include "fb.h"

FBCALL ssize_t fb_WstrInstrRev( const FB_WCHAR *src, const FB_WCHAR *patt, ssize_t start )
{
        if( (src != NULL) && (patt != NULL) )
        {
                ssize_t size_src = fb_wstr_Len(src);
                ssize_t size_patt = fb_wstr_Len(patt);
                ssize_t i, j;

                if( (size_src != 0) && (size_patt != 0) && (size_patt <= size_src) && (start != 0))
                {
                        /* handle signed/unsigned comparisons of start and size_* vars */
                        if( start < 0 )
                                start = size_src - size_patt + 1;
                        else if( start > size_src )
                                start = 0;
                        else if(start > size_src - size_patt)
                                start = size_src - size_patt + 1;
                        
                        /*
                                There is no wcsrstr() function, 
                                so instead do a brute force scan.
                        */

                        for( i=0; i<start; ++i ) 
                        {
                                for( j=0; j!=size_patt; ++j ) 
                                {
                                        if( src[start-i+j-1] != patt[j] )
                                                break;
                                }
                                if( j==size_patt )
                                        return start - i;
                        }
                }
        }
                
        return 0;
}