From 61cb79d19210a18b9d492e93a6d14950cada189b Mon Sep 17 00:00:00 2001
From: ligd <liguiding1@xiaomi.com>
Date: Tue, 14 Dec 2021 14:59:20 +0800
Subject: [PATCH] syslog_rpmsg: change head & tail NON-wrap

Signed-off-by: ligd <liguiding1@xiaomi.com>
---
 drivers/syslog/syslog_rpmsg.c | 47 ++++++++++++++---------------------
 1 file changed, 19 insertions(+), 28 deletions(-)

diff --git a/drivers/syslog/syslog_rpmsg.c b/drivers/syslog/syslog_rpmsg.c
index 9d1e24426b..adb520503a 100644
--- a/drivers/syslog/syslog_rpmsg.c
+++ b/drivers/syslog/syslog_rpmsg.c
@@ -43,10 +43,10 @@
  * Pre-processor definitions
  ****************************************************************************/
 
-#define SYSLOG_RPMSG_WORK_DELAY         MSEC2TICK(CONFIG_SYSLOG_RPMSG_WORK_DELAY)
+#define SYSLOG_RPMSG_WORK_DELAY MSEC2TICK(CONFIG_SYSLOG_RPMSG_WORK_DELAY)
 
-#define SYSLOG_RPMSG_COUNT(h, t, size)  (((h)>=(t)) ? (h)-(t) : (size)-((t)-(h)))
-#define SYSLOG_RPMSG_SPACE(h, t, size)  ((size) - 1 - SYSLOG_RPMSG_COUNT(h, t, size))
+#define SYSLOG_RPMSG_COUNT(p)   ((p)->head - (p)->tail)
+#define SYSLOG_RPMSG_SPACE(p)   ((p)->size - 1 - SYSLOG_RPMSG_COUNT(p))
 
 /****************************************************************************
  * Private Types
@@ -101,6 +101,7 @@ static void syslog_rpmsg_work(FAR void *priv_)
   irqstate_t flags;
   uint32_t space;
   size_t len;
+  size_t off;
   size_t len_end;
 
   if (is_rpmsg_ept_ready(&priv->ept))
@@ -120,8 +121,9 @@ static void syslog_rpmsg_work(FAR void *priv_)
   flags = enter_critical_section();
 
   space  -= sizeof(*msg);
-  len     = SYSLOG_RPMSG_COUNT(priv->head, priv->tail, priv->size);
-  len_end = priv->size - priv->tail;
+  len     = SYSLOG_RPMSG_COUNT(priv);
+  off     = priv->tail % priv->size;
+  len_end = priv->size - off;
 
   if (len > space)
     {
@@ -130,12 +132,12 @@ static void syslog_rpmsg_work(FAR void *priv_)
 
   if (len > len_end)
     {
-      memcpy(msg->data, &priv->buffer[priv->tail], len_end);
+      memcpy(msg->data, &priv->buffer[off], len_end);
       memcpy(msg->data + len_end, priv->buffer, len - len_end);
     }
   else
     {
-      memcpy(msg->data, &priv->buffer[priv->tail], len);
+      memcpy(msg->data, &priv->buffer[off], len);
     }
 
   priv->trans_len = len;
@@ -156,12 +158,8 @@ static void syslog_rpmsg_putchar(FAR struct syslog_rpmsg_s *priv, int ch,
   while (1)
     {
       next = priv->head + 1;
-      if (next >= priv->size)
-        {
-          next = 0;
-        }
 
-      if (next == priv->tail)
+      if (next - priv->tail >= priv->size)
         {
 #ifndef CONFIG_SYSLOG_RPMSG_OVERWRITE
           if (!up_interrupt_context() && !sched_idletask())
@@ -173,14 +171,9 @@ static void syslog_rpmsg_putchar(FAR struct syslog_rpmsg_s *priv, int ch,
             {
               /* Overwrite */
 
-              priv->buffer[priv->tail] = 0;
+              priv->buffer[priv->tail % priv->size] = 0;
               priv->tail += 1;
 
-              if (priv->tail >= priv->size)
-                {
-                  priv->tail = 0;
-                }
-
               if (priv->transfer)
                 {
                   priv->trans_len--;
@@ -195,14 +188,14 @@ static void syslog_rpmsg_putchar(FAR struct syslog_rpmsg_s *priv, int ch,
         }
     }
 
-  priv->buffer[priv->head] = ch & 0xff;
+  priv->buffer[priv->head % priv->size] = ch & 0xff;
   priv->head = next;
 
   if (last && !priv->suspend && !priv->transfer &&
           is_rpmsg_ept_ready(&priv->ept))
     {
       clock_t delay = SYSLOG_RPMSG_WORK_DELAY;
-      size_t space = SYSLOG_RPMSG_SPACE(priv->head, priv->tail, priv->size);
+      size_t space = SYSLOG_RPMSG_SPACE(priv);
 
       /* Start work immediately when data more then 75% and meet '\n' */
 
@@ -271,29 +264,27 @@ static int syslog_rpmsg_ept_cb(FAR struct rpmsg_endpoint *ept,
     {
       irqstate_t flags;
       ssize_t len_end;
+      size_t off;
       int sval;
 
       flags = enter_critical_section();
 
       if (priv->trans_len > 0)
         {
-          len_end = priv->size - priv->tail;
+          off = priv->tail % priv->size;
+          len_end = priv->size - off;
 
           if (priv->trans_len > len_end)
             {
-              memset(&priv->buffer[priv->tail], 0, len_end);
+              memset(&priv->buffer[off], 0, len_end);
               memset(priv->buffer, 0, priv->trans_len - len_end);
             }
           else
             {
-              memset(&priv->buffer[priv->tail], 0, priv->trans_len);
+              memset(&priv->buffer[off], 0, priv->trans_len);
             }
 
           priv->tail += priv->trans_len;
-          if (priv->tail >= priv->size)
-            {
-              priv->tail -= priv->size;
-            }
 
           nxsem_get_value(&priv->sem, &sval);
           while (sval++ < 0)
@@ -304,7 +295,7 @@ static int syslog_rpmsg_ept_cb(FAR struct rpmsg_endpoint *ept,
 
       priv->transfer = false;
 
-      if (SYSLOG_RPMSG_COUNT(priv->head, priv->tail, priv->size))
+      if (SYSLOG_RPMSG_COUNT(priv))
         {
           work_queue(HPWORK, &priv->work, syslog_rpmsg_work, priv, 0);
         }