X-Git-Url: https://diplodocus.org/git/nmh/blobdiff_plain/95a6664c9c034cecff0c13b325de93397e81f18d..522c91c2baad8d9575ba62d48487800e1e0e7203:/sbr/vector.c?ds=inline

diff --git a/sbr/vector.c b/sbr/vector.c
index 6ecca7ce..6afe62aa 100644
--- a/sbr/vector.c
+++ b/sbr/vector.c
@@ -19,7 +19,15 @@
 #include <h/mh.h>
 #include <h/utils.h>
 
-#define VEC_INIT_SIZE 256
+/* The default size of a struct bvector's bits, measured in bits.
+ * The struct's tiny member is used for storage. */
+#define BVEC_INIT_SIZE (sizeof *(((bvector_t)NULL)->tiny) * CHAR_BIT)
+
+/* The default number of char pointers in a struct svector. */
+#define SVEC_INIT_SIZE 256
+
+/* The default number of ints in a struct ivector. */
+#define IVEC_INIT_SIZE 256
 
 /*
  * These try to hide the type of the "bits" member of bvector.  But if
@@ -27,74 +35,87 @@
  * constants in the code below must also be changed to a 1 that's at
  * least as wide as the new type.
  */
-#define BVEC_WORD(vec, max) ((max) / (sizeof *vec->bits * CHAR_BIT))
-#define BVEC_OFFSET(vec, max) ((max) % (sizeof *vec->bits * CHAR_BIT))
-#define BVEC_BYTES(vec, n) \
-    ((BVEC_WORD (vec, n) + (BVEC_OFFSET (vec, n) == 0 ? 0 : 1))  * \
-    sizeof *vec->bits)
-
-struct bvector {
-    unsigned long *bits;
-    size_t maxsize;
-};
 
-static void bvector_resize (bvector_t, size_t);
+/* The *sizeof* struct bvector's bits member.  Not its size in bits. */
+#define BVEC_SIZEOF_BITS (sizeof *(((bvector_t)NULL)->bits))
+/* The number of bits held in one element of the bits member. */
+#define BVEC_BITS_BITS (BVEC_SIZEOF_BITS * CHAR_BIT)
+/* The index of bit n in struct bvector's bits member. */
+#define BVEC_WORD(n) ((n) / BVEC_BITS_BITS)
+/* The index of bit n within a single struct bvector's bits member. */
+#define BVEC_OFFSET(n) ((n) % BVEC_BITS_BITS)
+/* The number of elements bits needs to cover bit n, measured in bytes. */
+#define BVEC_BYTES(n) (((n) / BVEC_BITS_BITS + 1) * BVEC_SIZEOF_BITS)
+
+/* bvector_resize ensures the storage used for bits can cover bit
+ * newsize.  It always increases the size of the storage used for bits,
+ * even if newsize would have been covered by the existing storage.
+ * Thus it's normally only called when it's known the storage must grow. */
+static void bvector_resize (bvector_t vec, size_t newsize);
 
 bvector_t
-bvector_create (size_t init_size) {
+bvector_create (void) {
     bvector_t vec;
-    size_t bytes;
 
     /* See "wider than unsigned long" comment above. */
     assert (sizeof *vec->bits <= sizeof 1ul);
 
     NEW(vec);
-    bytes = BVEC_BYTES (vec, init_size  ?  init_size  :  VEC_INIT_SIZE);
-
-    vec->bits = mh_xcalloc (1, bytes);
-    vec->maxsize = bytes * CHAR_BIT;
+    bvector_init(vec);
 
     return vec;
 }
 
+void bvector_init(struct bvector *bv)
+{
+    bv->bits = bv->tiny;
+    bv->maxsize = BVEC_INIT_SIZE;
+    memset(bv->tiny, 0, sizeof bv->tiny);
+}
+
 void
 bvector_copy (bvector_t dest, bvector_t src) {
-    size_t bytes = BVEC_BYTES (dest, src->maxsize);
-
-    free (dest->bits);
-    dest->bits = mh_xmalloc (bytes);
+    size_t bytes = BVEC_BYTES(src->maxsize);
+
+    if (dest->bits != dest->tiny)
+        free(dest->bits);
+    if (bytes <= sizeof dest->tiny)
+        dest->bits = dest->tiny;
+    else
+        dest->bits = mh_xmalloc (bytes);
     memcpy (dest->bits, src->bits, bytes);
     dest->maxsize = src->maxsize;
 }
 
 void
 bvector_free (bvector_t vec) {
-    free (vec->bits);
+    bvector_fini(vec);
     free (vec);
 }
 
+void bvector_fini(struct bvector *bv)
+{
+    if (bv->bits != bv->tiny)
+        free(bv->bits);
+}
+
 void
 bvector_clear (bvector_t vec, size_t n) {
-    size_t word = BVEC_WORD (vec,n);
-    size_t offset = BVEC_OFFSET (vec, n);
-
-    if (n >= vec->maxsize)
-        bvector_resize (vec, n);
-
-    vec->bits[word] &= ~(1ul << offset);
+    if (n < vec->maxsize)
+        vec->bits[BVEC_WORD(n)] &= ~(1ul << BVEC_OFFSET(n));
 }
 
 
 void
 bvector_clear_all (bvector_t vec) {
-    memset (vec->bits, 0, BVEC_BYTES (vec, vec->maxsize));
+    memset (vec->bits, 0, BVEC_BYTES(vec->maxsize));
 }
 
 
 void
 bvector_set (bvector_t vec, size_t n) {
-    size_t word = BVEC_WORD (vec, n);
-    size_t offset = BVEC_OFFSET (vec, n);
+    size_t word = BVEC_WORD(n);
+    size_t offset = BVEC_OFFSET(n);
 
     if (n >= vec->maxsize)
         bvector_resize (vec, n);
@@ -103,31 +124,33 @@ bvector_set (bvector_t vec, size_t n) {
 
 unsigned int
 bvector_at (bvector_t vec, size_t i) {
-    size_t word = BVEC_WORD (vec, i);
-    size_t offset = BVEC_OFFSET (vec, i);
+    if (i < vec->maxsize)
+        return !!(vec->bits[BVEC_WORD(i)] & (1ul << BVEC_OFFSET(i)));
 
-    return i < vec->maxsize
-        ?  (vec->bits[word] & (1ul << offset) ? 1 : 0)
-        :  0;
+    return 0;
 }
 
 static void
-bvector_resize (bvector_t vec, size_t maxsize) {
-    size_t old_maxsize = vec->maxsize;
+bvector_resize (bvector_t vec, size_t newsize) {
+    size_t oldsize = vec->maxsize;
     size_t bytes;
-    size_t i;
 
-    while ((vec->maxsize *= 2) < maxsize)
+    while ((vec->maxsize *= 2) < newsize)
         ;
-    bytes = BVEC_BYTES (vec, vec->maxsize);
-    vec->bits = mh_xrealloc (vec->bits, bytes);
-    for (i = old_maxsize; i < vec->maxsize; ++i)
-        bvector_clear (vec, i);
+    bytes = BVEC_BYTES(vec->maxsize);
+    if (vec->bits == vec->tiny) {
+        vec->bits = mh_xmalloc(bytes);
+        memcpy(vec->bits, vec->tiny, sizeof vec->tiny);
+    } else
+        vec->bits = mh_xrealloc(vec->bits, bytes);
+
+    memset(vec->bits + (oldsize / BVEC_BITS_BITS), 0,
+        (vec->maxsize - oldsize) / CHAR_BIT);
 }
 
-const unsigned long *
-bvector_bits (bvector_t vec) {
-    return vec->bits;
+unsigned long
+bvector_first_bits (bvector_t vec) {
+    return *vec->bits;
 }
 
 
@@ -145,7 +168,7 @@ svector_create (size_t init_size) {
     size_t bytes;
 
     NEW(vec);
-    vec->maxsize = init_size ? init_size : VEC_INIT_SIZE;
+    vec->maxsize = init_size ? init_size : SVEC_INIT_SIZE;
     bytes = vec->maxsize * sizeof (char *);
     vec->strs = mh_xcalloc (1, bytes);
     vec->size = 0;
@@ -204,13 +227,12 @@ svector_size (svector_t vec) {
 static void
 svector_resize (svector_t vec, size_t maxsize) {
     size_t old_maxsize = vec->maxsize;
-    size_t i;
 
     while ((vec->maxsize *= 2) < maxsize)
         ;
     vec->strs = mh_xrealloc (vec->strs, vec->maxsize * sizeof (char *));
-    for (i = old_maxsize; i < vec->maxsize; ++i)
-        vec->strs[i] = NULL;
+    memset(vec->strs + old_maxsize, 0,
+        (vec->maxsize - old_maxsize) * sizeof *vec->strs);
 }
 
 
@@ -228,7 +250,7 @@ ivector_create (size_t init_size) {
     size_t bytes;
 
     NEW(vec);
-    vec->maxsize = init_size ? init_size : VEC_INIT_SIZE;
+    vec->maxsize = init_size ? init_size : IVEC_INIT_SIZE;
     bytes = vec->maxsize * sizeof (int);
     vec->ints = mh_xcalloc (1, bytes);
     vec->size = 0;
@@ -266,11 +288,10 @@ ivector_atp (ivector_t vec, size_t i) {
 static void
 ivector_resize (ivector_t vec, size_t maxsize) {
     size_t old_maxsize = vec->maxsize;
-    size_t i;
 
     while ((vec->maxsize *= 2) < maxsize)
         ;
     vec->ints = mh_xrealloc (vec->ints, vec->maxsize * sizeof (int));
-    for (i = old_maxsize; i < vec->maxsize; ++i)
-        vec->ints[i] = 0;
+    memset(vec->ints + old_maxsize, 0,
+        (vec->maxsize - old_maxsize) * sizeof *vec->ints);
 }