mood.c: Trivial cosmetics for int_sqrt().

[paraslash.git] / mood.c

diff --git a/mood.c b/mood.c
index 92bef0fa8c04554da7b442cb63dbfb561ee828bd..e9c5bd6e0e60ca55e5fc3bb4e67234bdf51fc193 100644 (file)
--- a/mood.c
+++ b/mood.c
@@ -84,32 +84,60 @@ struct mood {
  */
 static struct mood *current_mood;
 
-/**
- * Rough approximation to sqrt.
+/*
+ * Find the position of the most-significant set bit.
  *
- * \param x Integer of which to calculate the sqrt.
+ * Copied and slightly adapted from the linux source tree, version 4.9.39
+ * (2017-07).
+ */
+__a_const static uint32_t fls64(uint64_t v)
+{
+       int n = 63;
+       const uint64_t ones = ~(uint64_t)0U;
+
+       if ((v & (ones << 32)) == 0) {
+               n -= 32;
+               v <<= 32;
+       }
+       if ((v & (ones << (64 - 16))) == 0) {
+               n -= 16;
+               v <<= 16;
+       }
+       if ((v & (ones << (64 - 8))) == 0) {
+               n -= 8;
+               v <<= 8;
+       }
+       if ((v & (ones << (64 - 4))) == 0) {
+               n -= 4;
+               v <<= 4;
+       }
+       if ((v & (ones << (64 - 2))) == 0) {
+               n -= 2;
+               v <<= 2;
+       }
+       if ((v & (ones << (64 - 1))) == 0)
+               n -= 1;
+       return n;
+}
+
+/*
+ * Compute the integer square root floor(sqrt(x)).
  *
- * \return An integer res with res * res <= x.
+ * Taken 2007 from the linux source tree.
  */
 __a_const static uint64_t int_sqrt(uint64_t x)
 {
-       uint64_t op, res, one = 1;
-       op = x;
-       res = 0;
-
-       one = one << 62;
-       while (one > op)
-               one >>= 2;
+       uint64_t op = x, res = 0, one = 1;
 
+       one = one << (fls64(x) & ~one);
        while (one != 0) {
                if (op >= res + one) {
                        op = op - (res + one);
-                       res = res +  2 * one;
+                       res = res + 2 * one;
                }
                res /= 2;
                one /= 4;
        }
-//     PARA_NOTICE_LOG("sqrt(%llu) = %llu\n", x, res);
        return res;
 }
 
@@ -140,8 +168,8 @@ static bool get_item_score(struct mood_item *item, const struct afs_info *afsi,
 }
 
 /* returns 1 if row admissible, 0 if not, negative on errors */
-static int compute_mood_score(const struct osl_row *aft_row, struct mood *m,
-               long *result)
+static int row_is_admissible(const struct osl_row *aft_row, struct mood *m,
+               long *scorep)
 {
        struct mood_item *item;
        int ret;
@@ -154,13 +182,13 @@ static int compute_mood_score(const struct osl_row *aft_row, struct mood *m,
        if (!m)
                return -E_NO_MOOD;
        ret = get_afsi_of_row(aft_row, &afsi);
-       if (ret< 0)
+       if (ret < 0)
                return ret;
        ret = get_afhi_of_row(aft_row, &afhi);
-       if (ret< 0)
+       if (ret < 0)
                return ret;
        ret = get_audio_file_path_of_row(aft_row, &path);
-       if (ret< 0)
+       if (ret < 0)
                return ret;
        /* reject audio file if it matches any entry in the deny list */
        list_for_each_entry(item, &m->deny_list, mood_item_node) {
@@ -190,7 +218,7 @@ static int compute_mood_score(const struct osl_row *aft_row, struct mood *m,
        }
        if (score_arg_sum)
                score /= score_arg_sum;
-       *result = score;
+       *scorep = score;
        return 1;
 }
 
@@ -257,7 +285,6 @@ struct mood_line_parser_data {
  * <score> is either an integer or "random" which assigns a random score to
  * all matching files
  */
-
 static int parse_mood_line(char *mood_line, void *data)
 {
        struct mood_line_parser_data *mlpd = data;
@@ -566,7 +593,7 @@ static int add_if_admissible(struct osl_row *aft_row, void *data)
        int ret;
        long score = 0;
 
-       ret = compute_mood_score(aft_row, aa->m, &score);
+       ret = row_is_admissible(aft_row, aa->m, &score);
        if (ret <= 0)
                return ret;
        if (statistics.num >= aa->size) {
@@ -625,7 +652,8 @@ _static_inline_ int64_t update_quadratic_deviation(int64_t n, int64_t old_qd,
        return old_qd + delta * (sigma - 2 * old_sum / n - delta / n);
 }
 
-static int update_afs_statistics(struct afs_info *old_afsi, struct afs_info *new_afsi)
+static int update_afs_statistics(struct afs_info *old_afsi,
+               struct afs_info *new_afsi)
 {
        unsigned n;
        int ret = get_num_admissible_files(&n);
@@ -712,7 +740,7 @@ static int mood_update_audio_file(const struct osl_row *aft_row,
        if (ret < 0)
                return ret;
        was_admissible = ret;
-       ret = compute_mood_score(aft_row, current_mood, &score);
+       ret = row_is_admissible(aft_row, current_mood, &score);
        if (ret < 0)
                return ret;
        is_admissible = (ret > 0);
@@ -846,6 +874,7 @@ out:
        free(aa.array);
        return ret;
 }
+
 /*
  * Close and re-open the current mood.
  *