diff --git a/include/picrin/xvect.h b/include/picrin/xvect.h
index bd72070e..ec68a2cb 100644
--- a/include/picrin/xvect.h
+++ b/include/picrin/xvect.h
@@ -2,51 +2,40 @@
 #define XVECT_H__
 
 /*
- * Copyright (c) 2014 by Yuichi Nishiwaki <yuichi@idylls.jp>
+ * Copyright (c) 2014 by Yuichi Nishiwaki <yuichi@idyll.jp>
  */
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
 
-#include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
 
 typedef struct xvect {
   char *data;
-  size_t size, mask, head, tail, width;
+  size_t size, capa, width;
 } xvect;
 
 static inline void xv_init(xvect *, size_t);
 static inline void xv_destroy(xvect *);
 
-static inline size_t xv_size(xvect *);
-
 static inline void xv_reserve(xvect *, size_t);
-static inline void xv_shrink(xvect *, size_t);
 
 static inline void *xv_get(xvect *, size_t);
 static inline void xv_set(xvect *, size_t, void *);
 
 static inline void xv_push(xvect *, void *);
+static inline void *xv_peek(xvect *);
 static inline void *xv_pop(xvect *);
 
-static inline void *xv_shift(xvect *);
-static inline void xv_unshift(xvect *, void *);
-
-static inline void xv_splice(xvect *, size_t, ptrdiff_t);
-static inline void xv_insert(xvect *, size_t, void *);
-
 static inline void
 xv_init(xvect *x, size_t width)
 {
   x->data = NULL;
-  x->width = width;
   x->size = 0;
-  x->mask = -1;
-  x->head = 0;
-  x->tail = 0;
+  x->capa = 0;
+  x->width = width;
 }
 
 static inline void
@@ -55,127 +44,44 @@ xv_destroy(xvect *x)
   free(x->data);
 }
 
-static inline size_t
-xv_size(xvect *x)
-{
-  return x->tail < x->head
-    ? x->tail + x->size - x->head
-    : x->tail - x->head;
-}
-
-static inline size_t
-xv_round2(size_t x)
-{
-  x -= 1;
-  x |= (x >> 1);
-  x |= (x >> 2);
-  x |= (x >> 4);
-  x |= (x >> 8);
-  x |= (x >> 16);
-  x |= (x >> 32);
-  x++;
-  return x;
-}
-
 static inline void
-xv_rotate(xvect *x)
+xv_reserve(xvect *x, size_t newcapa)
 {
-  if (x->tail < x->head) {
-    char buf[x->size * x->width];
-
-    /* perform rotation */
-    memcpy(buf, x->data, sizeof buf);
-    memcpy(x->data, buf + x->head * x->width, (x->size - x->head) * x->width);
-    memcpy(x->data + (x->size - x->head) * x->width, buf, x->tail * x->width);
-    x->tail = x->size - x->head + x->tail;
-    x->head = 0;
-  }
-}
-
-static inline void
-xv_adjust(xvect *x, size_t size)
-{
-  size = xv_round2(size);
-  if (size != x->size) {
-    xv_rotate(x);
-    x->data = realloc(x->data, size * x->width);
-    x->size = size;
-    x->mask = size - 1;
-  }
-}
-
-static inline void
-xv_reserve(xvect *x, size_t mincapa)
-{
-  if (x->size < mincapa + 1) {
-    xv_adjust(x, mincapa + 1);  /* capa == size - 1 */
-  }
-}
-
-static inline void
-xv_shrink(xvect *x, size_t maxcapa)
-{
-  if (x->size > maxcapa + 1) {
-    xv_adjust(x, maxcapa + 1);  /* capa == size - 1 */
-  }
+  x->data = realloc(x->data, newcapa * x->width);
+  x->capa = newcapa;
 }
 
 static inline void *
 xv_get(xvect *x, size_t i)
 {
-  return x->data + ((x->head + x->size + i) & x->mask) * x->width;
+  return x->data + i * x->width;
 }
 
 static inline void
 xv_set(xvect *x, size_t i, void *src)
 {
-  memcpy(xv_get(x, i), src, x->width);
+  memcpy(x->data + i * x->width, src, x->width);
 }
 
 static inline void
 xv_push(xvect *x, void *src)
 {
-  xv_reserve(x, xv_size(x) + 1);
-  xv_set(x, xv_size(x), src);
-  x->tail = (x->tail + 1) & x->mask;
+  if (x->capa <= x->size + 1) {
+    xv_reserve(x, x->size * 2 + 1);
+  }
+  xv_set(x, x->size++, src);
+}
+
+static inline void *
+xv_peek(xvect *x)
+{
+  return xv_get(x, x->size);
 }
 
 static inline void *
 xv_pop(xvect *x)
 {
-  x->tail = (x->tail + x->size - 1) & x->mask;
-  return xv_get(x, xv_size(x));
-}
-
-static inline void *
-xv_shift(xvect *x)
-{
-  x->head = (x->head + 1) & x->mask;
-  return xv_get(x, -1);
-}
-
-static inline void
-xv_unshift(xvect *x, void *src)
-{
-  xv_reserve(x, xv_size(x) + 1);
-  xv_set(x, -1, src);
-  x->head = (x->head + x->size - 1) & x->mask;
-}
-
-static inline void
-xv_splice(xvect *x, size_t i, ptrdiff_t c)
-{
-  xv_reserve(x, xv_size(x) - c);
-  xv_rotate(x);
-  memmove(xv_get(x, i), xv_get(x, i + c), (xv_size(x) - i - c) * x->width);
-  x->tail -= c;
-}
-
-static inline void
-xv_insert(xvect *x, size_t i, void *src)
-{
-  xv_splice(x, i, -1);
-  xv_set(x, i, src);
+  return xv_get(x, --x->size);
 }
 
 #if defined(__cplusplus)