[Qemu-devel] [PATCH 1/5] qemu-char: Add new char backend CircularMemCharDriver

[Lei Li]

Signed-off-by: Lei Li <address@hidden>
---
 qemu-char.c |   72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 72 insertions(+), 0 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index b082bae..b174da1 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2588,6 +2588,78 @@ size_t qemu_chr_mem_osize(const CharDriverState *chr)
     return d->outbuf_size;
 }
 
+/*********************************************************/
+/*CircularMemoryr chardev*/
+
+typedef struct {
+    size_t size;
+    size_t producer;
+    size_t consumer;
+    uint8_t *cbuf;
+} CirMemCharDriver;
+
+static bool cirmem_chr_is_empty(const CharDriverState *chr)
+{
+    const CirMemCharDriver *d = chr->opaque;
+
+    return d->producer == d->consumer;
+}
+
+static bool cirmem_chr_is_full(const CharDriverState *chr)
+{
+    const CirMemCharDriver *d = chr->opaque;
+
+    return (d->producer - d->consumer) >= d->size;
+}
+
+static int cirmem_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
+{
+    CirMemCharDriver *d = chr->opaque;
+    int i;
+
+    if (len < 0) {
+        return -1;
+    }
+
+    /* The size should be a power of 2. */
+    for (i = 0; i < len; i++ ) {
+        d->cbuf[d->producer % d->size] = buf[i];
+        d->producer++;
+    }
+
+    return 0;
+}
+
+static int cirmem_chr_read(CharDriverState *chr, uint8_t *buf, int len)
+{
+    CirMemCharDriver *d = chr->opaque;
+    int i;
+
+    if (cirmem_chr_is_empty(chr) || len < 0) {
+        return -1;
+    }
+
+    if (len > d->size) {
+        len = d->size;
+    }
+
+    for (i = 0; i < len; i++) {
+        buf[i] = d->cbuf[d->consumer % d->size];
+        d->consumer++;
+    }
+
+    return 0;
+}
+
+static void cirmem_chr_close(struct CharDriverState *chr)
+{
+    CirMemCharDriver *d = chr->opaque;
+
+    g_free(d);
+    g_free(chr->opaque);
+    chr->opaque = NULL;
+}
+
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)
 {
     char host[65], port[33], width[8], height[8];
-- 
1.7.7.6