From 1bad9713611010563deb083c631c7dfe32682acf Mon Sep 17 00:00:00 2001
From: "martin.holst@gmail.com"
<martin.holst@gmail.com@ef4ab9da-24cd-11de-8aaa-f3a34680c41f>
Date: Thu, 6 Jun 2013 18:30:00 +0000
Subject: [PATCH] Fixed so storeCommand/getCommand are multithread-safe (at
least dual-thread). Hopefully.
http://www.proxmark.org/forum/viewtopic.php?pid=7400#p7400
---
client/cmdmain.c | 21 ++++-----------------
1 file changed, 4 insertions(+), 17 deletions(-)
diff --git a/client/cmdmain.c b/client/cmdmain.c
index 85a0e0ca..972558c3 100644
--- a/client/cmdmain.c
+++ b/client/cmdmain.c
@@ -39,7 +39,7 @@ static UsbCommand cmdBuffer[CMD_BUFFER_SIZE];
//Points to the next empty position to write to
static int cmd_head;//Starts as 0
//Points to the position of the last unread command
-static int cmd_tail = -1;//Starts as -1
+static int cmd_tail;//Starts as 0
static command_t CommandTable[] =
{
@@ -211,7 +211,7 @@ void UsbCommandReceived(UsbCommand *UC)
*/
void storeCommand(UsbCommand *command)
{
- if(cmd_head == cmd_tail)
+ if( ( cmd_head+1) % CMD_BUFFER_SIZE == cmd_tail)
{
//If these two are equal, we're about to overwrite in the
// circular buffer.
@@ -221,14 +221,7 @@ void storeCommand(UsbCommand *command)
UsbCommand* destination = &cmdBuffer[cmd_head];
memcpy(destination, command, sizeof(UsbCommand));
- //Also, if cmd_tail is still -1 because the buffer was
- // previously empty, set it to head
- if(cmd_tail < 0) {
- cmd_tail = cmd_head;
- }
-
- cmd_head++; //increment head
- cmd_head %= CMD_BUFFER_SIZE;//wrap around
+ cmd_head = (cmd_head +1) % CMD_BUFFER_SIZE; //increment head and wrap
}
/**
@@ -239,7 +232,7 @@ void storeCommand(UsbCommand *command)
int getCommand(UsbCommand* response)
{
//If head == tail, there's nothing to read, or if we just got initialized
- if(cmd_head == cmd_tail || cmd_tail == -1){
+ if(cmd_head == cmd_tail){
return 0;
}
//Pick out the next unread command
@@ -247,12 +240,6 @@ int getCommand(UsbCommand* response)
memcpy(response, last_unread, sizeof(UsbCommand));
//Increment tail - this is a circular buffer, so modulo buffer size
cmd_tail = (cmd_tail +1 ) % CMD_BUFFER_SIZE;
- //In order to detect when the buffer overwrites itself, we set the
- // tail to -1 whenever it 'catches up' with head : this means the buffer is empty.
- // Otherwise, head==tail could mean both: either empty or full.
- if(cmd_tail == cmd_head){
- cmd_tail = -1 ;
- }
return 1;
--
2.39.5