Clean up the use of switch cases.

diff --git a/gzread.c b/gzread.c
index b198a44..bbabf52 100644
--- a/gzread.c
+++ b/gzread.c

@@ -267,6 +267,10 @@
             strm->next_out = state->out;
             if (gz_decomp(state) == -1)
                 return -1;
+            break;
+        default:
+            gz_error(state, Z_STREAM_ERROR, "state corrupt");
+            return -1;
         }
     } while (state->x.have == 0 && (!state->eof || strm->avail_in));
     return 0;

diff --git a/infback.c b/infback.c
index 518bf3e..8cb7654 100644
--- a/infback.c
+++ b/infback.c

@@ -252,7 +252,7 @@
                         state->last ? " (last)" : ""));
                 state->mode = TABLE;
                 break;
-            case 3:
+            default:
                 strm->msg = (z_const char *)"invalid block type";
                 state->mode = BAD;
             }

diff --git a/inflate.c b/inflate.c
index f55949e..6baa4df 100644
--- a/inflate.c
+++ b/inflate.c

@@ -738,7 +738,7 @@
                         state->last ? " (last)" : ""));
                 state->mode = TABLE;
                 break;
-            case 3:
+            default:
                 strm->msg = (z_const char *)"invalid block type";
                 state->mode = BAD;
             }

diff --git a/inftrees.c b/inftrees.c
index 6b6f8dc..2a46871 100644
--- a/inftrees.c
+++ b/inftrees.c

@@ -57,9 +57,9 @@
     unsigned mask;              /* mask for low root bits */
     code here;                  /* table entry for duplication */
     code FAR *next;             /* next available space in table */
-    const unsigned short FAR *base;     /* base value table to use */
-    const unsigned short FAR *extra;    /* extra bits table to use */
-    unsigned match;             /* use base and extra for symbol >= match */
+    const unsigned short FAR *base = NULL;  /* base value table to use */
+    const unsigned short FAR *extra = NULL; /* extra bits table to use */
+    unsigned match = 0;         /* use base and extra for symbol >= match */
     unsigned short count[MAXBITS+1];    /* number of codes of each length */
     unsigned short offs[MAXBITS+1];     /* offsets in table for each length */
     static const unsigned short lbase[31] = { /* Length codes 257..285 base */
@@ -185,7 +185,6 @@
     /* set up for code type */
     switch (type) {
     case CODES:
-        base = extra = work;    /* dummy value--not used */
         match = 20;
         break;
     case LENS:
@@ -193,10 +192,9 @@
         extra = lext;
         match = 257;
         break;
-    default:    /* DISTS */
+    case DISTS:
         base = dbase;
         extra = dext;
-        match = 0;
     }
 
     /* initialize state for loop */