connection: Factor out circular buffer functionality

diff --git a/connection.c b/connection.c
index af09947..576becf 100644 (file)
--- a/connection.c
+++ b/connection.c
@@ -43,6 +43,8 @@ struct wl_buffer {
        int head, tail;
 };
 
+#define MASK(i) ((i) & 4095)
+
 struct wl_connection {
        struct wl_buffer in, out;
        int fd;
@@ -50,6 +52,86 @@ struct wl_connection {
        wl_connection_update_func_t update;
 };
 
+static void
+wl_buffer_put(struct wl_buffer *b, const void *data, size_t count)
+{
+       int head, size;
+
+       head = MASK(b->head);
+       if (head + count <= sizeof b->data) {
+               memcpy(b->data + head, data, count);
+       } else {
+               size = sizeof b->data - head;
+               memcpy(b->data + head, data, size);
+               memcpy(b->data, (const char *) data + size, count - size);
+       }
+
+       b->head += count;
+}
+
+static void
+wl_buffer_put_iov(struct wl_buffer *b, struct iovec *iov, int *count)
+{
+       int head, tail;
+
+       head = MASK(b->head);
+       tail = MASK(b->tail);
+       if (head < tail) {
+               iov[0].iov_base = b->data + head;
+               iov[0].iov_len = tail - head;
+               *count = 1;
+       } else if (tail == 0) {
+               iov[0].iov_base = b->data + head;
+               iov[0].iov_len = sizeof b->data - head;
+               *count = 1;
+       } else {
+               iov[0].iov_base = b->data + head;
+               iov[0].iov_len = sizeof b->data - head;
+               iov[1].iov_base = b->data;
+               iov[1].iov_len = tail;
+               *count = 2;
+       }
+}
+
+static void
+wl_buffer_get_iov(struct wl_buffer *b, struct iovec *iov, int *count)
+{
+       int head, tail;
+
+       head = MASK(b->head);
+       tail = MASK(b->tail);
+       if (tail < head) {
+               iov[0].iov_base = b->data + tail;
+               iov[0].iov_len = head - tail;
+               *count = 1;
+       } else if (head == 0) {
+               iov[0].iov_base = b->data + tail;
+               iov[0].iov_len = sizeof b->data - tail;
+               *count = 1;
+       } else {
+               iov[0].iov_base = b->data + tail;
+               iov[0].iov_len = sizeof b->data - tail;
+               iov[1].iov_base = b->data;
+               iov[1].iov_len = head;
+               *count = 2;
+       }
+}
+
+static void
+wl_buffer_copy(struct wl_buffer *b, void *data, size_t count)
+{
+       int tail, size;
+
+       tail = MASK(b->tail);
+       if (tail + count <= sizeof b->data) {
+               memcpy(data, b->data + tail, count);
+       } else {
+               size = sizeof b->data - tail;
+               memcpy(data, b->data + tail, size);
+               memcpy((char *) data + size, b->data, count - size);
+       }
+}
+
 struct wl_connection *
 wl_connection_create(int fd,
                     wl_connection_update_func_t update,
@@ -80,67 +162,35 @@ wl_connection_destroy(struct wl_connection *connection)
 void
 wl_connection_copy(struct wl_connection *connection, void *data, size_t size)
 {
-       struct wl_buffer *b;
-       int tail, rest;
-
-       b = &connection->in;
-       tail = b->tail;
-       if (tail + size <= ARRAY_LENGTH(b->data)) {
-               memcpy(data, b->data + tail, size);
-       } else { 
-               rest = ARRAY_LENGTH(b->data) - tail;
-               memcpy(data, b->data + tail, rest);
-               memcpy(data + rest, b->data, size - rest);
-       }
+       wl_buffer_copy(&connection->in, data, size);
 }
 
 void
 wl_connection_consume(struct wl_connection *connection, size_t size)
 {
-       struct wl_buffer *b;
-       int tail, rest;
-
-       b = &connection->in;
-       tail = b->tail;
-       if (tail + size <= ARRAY_LENGTH(b->data)) {
-               b->tail += size;
-       } else { 
-               rest = ARRAY_LENGTH(b->data) - tail;
-               b->tail = size - rest;
-       }
+       connection->in.tail += size;
 }
 
 int wl_connection_data(struct wl_connection *connection, uint32_t mask)
 {
-       struct wl_buffer *b;
        struct iovec iov[2];
        struct msghdr msg;
-       int len, head, tail, count, size, available;
+       int len, count;
 
        if (mask & WL_CONNECTION_READABLE) {
-               b = &connection->in;
-               head = connection->in.head;
-               if (head < b->tail) {
-                       iov[0].iov_base = b->data + head;
-                       iov[0].iov_len = b->tail - head;
-                       count = 1;
-               } else {
-                       size = ARRAY_LENGTH(b->data) - head;
-                       iov[0].iov_base = b->data + head;
-                       iov[0].iov_len = size;
-                       iov[1].iov_base = b->data;
-                       iov[1].iov_len = b->tail;
-                       count = 2;
-               }
+               wl_buffer_put_iov(&connection->in, iov, &count);
+
+               msg.msg_name = NULL;
+               msg.msg_namelen = 0;
+               msg.msg_iov = iov;
+               msg.msg_iovlen = count;
+               msg.msg_control = NULL;
+               msg.msg_controllen = 0;
+
                do {
-                       msg.msg_name = NULL;
-                       msg.msg_namelen = 0;
-                       msg.msg_iov = iov;
-                       msg.msg_iovlen = count;
-                       msg.msg_control = NULL;
-                       msg.msg_controllen = 0;
                        len = recvmsg(connection->fd, &msg, 0);
                } while (len < 0 && errno == EINTR);
+
                if (len < 0) {
                        fprintf(stderr,
                                "read error from connection %p: %m (%d)\n",
@@ -149,90 +199,47 @@ int wl_connection_data(struct wl_connection *connection, uint32_t mask)
                } else if (len == 0) {
                        /* FIXME: Handle this better? */
                        return -1;
-               } else if (head + len <= ARRAY_LENGTH(b->data)) {
-                       b->head += len;
-               } else {
-                       b->head = head + len - ARRAY_LENGTH(b->data);
                }
 
-               /* We know we have data in the buffer at this point,
-                * so if head equals tail, it means the buffer is
-                * full. */
-
-               available = b->head - b->tail;
-               if (available == 0)
-                       available = sizeof b->data;
-               else if (available < 0)
-                       available += ARRAY_LENGTH(b->data);
-       } else {
-               available = 0;
+               connection->in.head += len;
        }       
 
        if (mask & WL_CONNECTION_WRITABLE) {
-               b = &connection->out;
-               tail = b->tail;
-               if (tail < b->head) {
-                       iov[0].iov_base = b->data + tail;
-                       iov[0].iov_len = b->head - tail;
-                       count = 1;
-               } else {
-                       size = ARRAY_LENGTH(b->data) - tail;
-                       iov[0].iov_base = b->data + tail;
-                       iov[0].iov_len = size;
-                       iov[1].iov_base = b->data;
-                       iov[1].iov_len = b->head;
-                       count = 2;
-               }
+               wl_buffer_get_iov(&connection->out, iov, &count);
+
+               msg.msg_name = NULL;
+               msg.msg_namelen = 0;
+               msg.msg_iov = iov;
+               msg.msg_iovlen = count;
+               msg.msg_control = NULL;
+               msg.msg_controllen = 0;
+
                do {
-                       msg.msg_name = NULL;
-                       msg.msg_namelen = 0;
-                       msg.msg_iov = iov;
-                       msg.msg_iovlen = count;
-                       msg.msg_control = NULL;
-                       msg.msg_controllen = 0;
                        len = sendmsg(connection->fd, &msg, 0);
                } while (len < 0 && errno == EINTR);
+
                if (len < 0) {
                        fprintf(stderr, "write error for connection %p: %m\n", connection);
                        return -1;
-               } else if (tail + len <= ARRAY_LENGTH(b->data)) {
-                       b->tail += len;
-               } else {
-                       b->tail = tail + len - ARRAY_LENGTH(b->data);
                }
 
-               /* We just took data out of the buffer, so at this
-                * point if head equals tail, the buffer is empty. */
-
-               if (b->tail == b->head)
+               connection->out.tail += len;
+               if (connection->out.tail == connection->out.head)
                        connection->update(connection,
                                           WL_CONNECTION_READABLE,
                                           connection->data);
        }
 
-       return available;
+       return connection->in.head - connection->in.tail;
 }
 
 void
-wl_connection_write(struct wl_connection *connection, const void *data, size_t count)
+wl_connection_write(struct wl_connection *connection,
+                   const void *data, size_t count)
 {
-       struct wl_buffer *b;
-       size_t size;
-       int head;
-
-       b = &connection->out;
-       head = b->head;
-       if (head + count <= ARRAY_LENGTH(b->data)) {
-               memcpy(b->data + head, data, count);
-               b->head += count;
-       } else {
-               size = ARRAY_LENGTH(b->data) - head;
-               memcpy(b->data + head, data, size);
-               memcpy(b->data, data + size, count - size);
-               b->head = count - size;
-       }
+       wl_buffer_put(&connection->out, data, count);
 
-       if (b->tail == head)
+       if (connection->out.head - connection->out.tail == count)
                connection->update(connection,
                                   WL_CONNECTION_READABLE |
                                   WL_CONNECTION_WRITABLE,