Add ring buffer object

The new ring buffer object will be used to buffer a byte-stream between
two sockets.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

diff --git a/Makefile.am b/Makefile.am
index 4323ea1..ee492f0 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -37,6 +37,7 @@ nodist_libkmscon_core_la_SOURCES = \
        src/output_shaders.c
 
 libkmscon_core_la_SOURCES = \
+       src/misc.c src/misc.h \
        src/console.c src/console.h \
        src/output.c src/output.h \
        src/output_context.c \

diff --git a/src/misc.c b/src/misc.c
new file mode 100644 (file)
index 0000000..8089822
--- /dev/null
+++ b/src/misc.c
@@ -0,0 +1,166 @@
+/*
+ * kmscon - Miscellaneous Helpers
+ *
+ * Copyright (c) 2011 David Herrmann <dh.herrmann@googlemail.com>
+ * Copyright (c) 2011 University of Tuebingen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Miscellaneous Helpers
+ * Rings: Rings are used to buffer a byte-stream of data. It works like a FIFO
+ * queue but in-memory.
+ */
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define RING_SIZE 512
+
+struct ring_entry {
+       struct ring_entry *next;
+       size_t len;
+       char buf[];
+};
+
+struct kmscon_ring {
+       struct ring_entry *first;
+       struct ring_entry *last;
+};
+
+int kmscon_ring_new(struct kmscon_ring **out)
+{
+       struct kmscon_ring *ring;
+
+       if (!out)
+               return -EINVAL;
+
+       ring = malloc(sizeof(*ring));
+       if (!ring)
+               return -ENOMEM;
+
+       memset(ring, 0, sizeof(*ring));
+
+       *out = ring;
+       return 0;
+}
+
+void kmscon_ring_free(struct kmscon_ring *ring)
+{
+       struct ring_entry *tmp;
+
+       if (!ring)
+               return;
+
+       while (ring->first) {
+               tmp = ring->first;
+               ring->first = tmp->next;
+               free(tmp);
+       }
+       free(ring);
+}
+
+bool kmscon_ring_is_empty(struct kmscon_ring *ring)
+{
+       if (!ring)
+               return false;
+
+       return ring->first;
+}
+
+int kmscon_ring_write(struct kmscon_ring *ring, const char *val, size_t len)
+{
+       struct ring_entry *ent;
+       size_t space, cp;
+
+       if (!ring || !val || !len)
+               return -EINVAL;
+
+next:
+       ent = ring->last;
+       if (!ent || ent->len >= RING_SIZE) {
+               ent = malloc(sizeof(*ent) + RING_SIZE);
+               if (!ent)
+                       return -ENOMEM;
+
+               ent->len = 0;
+               ent->next = NULL;
+               if (ring->last)
+                       ring->last->next = ent;
+               else
+                       ring->first = ent;
+               ring->last = ent;
+       }
+
+       space = RING_SIZE - ent->len;
+       if (len >= space)
+               cp = space;
+       else
+               cp = len;
+
+       memcpy(&ent->buf[ent->len], val, cp);
+       ent->len += cp;
+
+       val = &val[cp];
+       len -= cp;
+       if (len > 0)
+               goto next;
+
+       return 0;
+}
+
+const char *kmscon_ring_peek(struct kmscon_ring *ring, size_t *len)
+{
+       if (!ring || !ring->first)
+               return NULL;
+
+       *len = ring->first->len;
+       return ring->first->buf;
+}
+
+void kmscon_ring_drop(struct kmscon_ring *ring, size_t len)
+{
+       struct ring_entry *ent;
+
+       if (!ring || !len)
+               return;
+
+next:
+       ent = ring->first;
+       if (!ent)
+               return;
+
+       if (len >= ent->len) {
+               len -= ent->len;
+               ring->first = ent->next;
+               free(ent);
+               if (!ring->first)
+                       ring->last = NULL;
+
+               if (len)
+                       goto next;
+       } else {
+               memmove(ent->buf, &ent->buf[len], ent->len - len);
+               ent->len -= len;
+       }
+}

diff --git a/src/misc.h b/src/misc.h
new file mode 100644 (file)
index 0000000..ee53f27
--- /dev/null
+++ b/src/misc.h
@@ -0,0 +1,48 @@
+/*
+ * kmscon - Miscellaneous Helpers
+ *
+ * Copyright (c) 2011 David Herrmann <dh.herrmann@googlemail.com>
+ * Copyright (c) 2011 University of Tuebingen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Miscellaneous Helpers
+ * This provides several helper objects like memory-rings or similar.
+ */
+
+#ifndef KMSCON_MISC_H
+#define kMSCON_MISC_H
+
+#include <stdbool.h>
+#include <stdlib.h>
+
+struct kmscon_ring;
+
+int kmscon_ring_new(struct kmscon_ring **out);
+void kmscon_ring_free(struct kmscon_ring *ring);
+bool kmscon_ring_is_empty(struct kmscon_ring *ring);
+
+int kmscon_ring_write(struct kmscon_ring *ring, const char *val, size_t len);
+const char *kmscon_ring_peek(struct kmscon_ring *ring, size_t *len);
+void kmscon_ring_drop(struct kmscon_ring *ring, size_t len);
+
+#endif /* KMSCON_MISC_H */