- php_u_stristr: Code comments

diff --git a/ext/standard/string.c b/ext/standard/string.c
index cc0133cda02e26c552c52b9d3833f8bb4a52375d..f9762047f5533cb211b895f427a4343f03ac2964 100644 (file)
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -1924,20 +1924,33 @@ PHPAPI UChar *php_u_stristr(UChar *s, UChar *t, int32_t s_len, int32_t t_len)
 
        /* Have to do this by hand since lower-casing can change lengths
           by changing codepoints, and an offset within the lower-case &
-          upper-case strings might be different codepoints
+          upper-case strings might be different codepoints.
+
+          Find an occurrence of the first codept of 't' in 's', and
+          starting from this point, match the rest of the codepts of 't'
+          with those in 's'. Comparisons are performed against lower-case
+          equivalents of the codepoints being matched.
+
+          'i' & 'j' are indices used for extracting codepts 'ch1' &
+          'ch2'. 'last' is offset in 's' where the search for 't'
+          started, and indicates beginning of 't' in 's' for a successful
+          match.
        */
+
        i = 0;
        while (i <= (s_len-t_len)) {
                last = i;
                U16_NEXT(s, i, s_len, ch1);
-               U16_GET(t, 0, 0, t_len, ch2);
+               j = 0;
+               U16_NEXT(t, j, t_len, ch2);
                if (u_tolower(ch1) == u_tolower(ch2)) {
-                       j = 0;
-                       U16_FWD_1(t, j, t_len);
                        while (j < t_len) {
                                U16_NEXT(s, i, s_len, ch1);
                                U16_NEXT(t, j, t_len, ch2);
                                if (u_tolower(ch1) != u_tolower(ch2)) {
+                                       /* U16_NEXT() incr 'i' beyond 'ch1', re-adjust to
+                                          restart compare
+                                       */
                                        U16_BACK_1(s, 0, i);
                                        break;
                                }