stb_vorbis: fix signed/unsigned comparison

stb_vorbis.c

@@ -930,7 +930,7 @@ static void crc32_init(void)
    uint32 s;
    for(i=0; i < 256; i++) {
       for (s=i<<24, j=0; j < 8; ++j)
-         s = (s << 1) ^ (s >= (1<<31) ? CRC32_POLY : 0);
+         s = (s << 1) ^ (s >= (1U<<31) ? CRC32_POLY : 0);
       crc_table[i] = s;
    }
 }
@@ -964,15 +964,15 @@ static int ilog(int32 n)
    static signed char log2_4[16] = { 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4 };
 
    // 2 compares if n < 16, 3 compares otherwise (4 if signed or n > 1<<29)
-   if (n < (1U << 14))
-        if (n < (1U <<  4))        return     0 + log2_4[n      ];
-        else if (n < (1U <<  9))      return  5 + log2_4[n >>  5];
+   if (n < (1 << 14))
+        if (n < (1 <<  4))        return     0 + log2_4[n      ];
+        else if (n < (1 <<  9))      return  5 + log2_4[n >>  5];
              else                     return 10 + log2_4[n >> 10];
-   else if (n < (1U << 24))
-             if (n < (1U << 19))      return 15 + log2_4[n >> 15];
+   else if (n < (1 << 24))
+             if (n < (1 << 19))      return 15 + log2_4[n >> 15];
              else                     return 20 + log2_4[n >> 20];
-        else if (n < (1U << 29))      return 25 + log2_4[n >> 25];
-             else if (n < (1U << 31)) return 30 + log2_4[n >> 30];
+        else if (n < (1 << 29))      return 25 + log2_4[n >> 25];
+             else if (n < (1 << 31)) return 30 + log2_4[n >> 30];
                   else                return 0; // signed n returns 0
 }
 
@@ -1396,7 +1396,7 @@ static int start_page_no_capturepattern(vorb *f)
       return error(f, VORBIS_unexpected_eof);
    // assume we _don't_ know any the sample position of any segments
    f->end_seg_with_known_loc = -2;
-   if (loc0 != ~0 || loc1 != ~0) {
+   if (loc0 != ~0U || loc1 != ~0U) {
       int i;
       // determine which packet is the last one that will complete
       for (i=f->segment_count-1; i >= 0; --i)
@@ -4328,7 +4328,7 @@ static int vorbis_search_for_page_pushdata(vorb *f, uint8 *data, int data_len)
             f->next_seg = -1;       // start a new page
             f->current_loc = f->scan[i].sample_loc; // set the current sample location
                                     // to the amount we'd have decoded had we decoded this page
-            f->current_loc_valid = f->current_loc != ~0;
+            f->current_loc_valid = f->current_loc != ~0U;
             return data_len;
          }
          // delete entry