Changes between Version 128 and Version 129 of library_stdio

Timestamp:

Oct 18, 2015, 5:47:54 PM (10 years ago)

Author:

alain

Comment:

--

library_stdio

@@ -410 +410 @@
 
  === 2) void '''giet_fbf_alloc'''() ===
-This blocking function allows the calling thread to get exclusive ownership of the shared FBF peripheral. It returns only when the lock has been taken.
+This blocking function allows the calling thread to get exclusive ownership of the shared FBF peripheral.
+It returns only when the lock has been taken.
 All theads in the same space as the calling thread can access concurrently the frame buffer, under the user responsibility.
 This lock is released when the thread completes execution, after a giet_pthread_exit(), or a giet_pthread_kill().
 
- === 3) void '''giet_fbf_cma_alloc'''()
-This function allocates a private CMA channel  to the calling thread, and registers the channel index
-in the thread context.
-The threadthread exit if no CMA channel available
-
- === 4) void '''giet_fbf_cma_init_buf'''( void* buf0_vbase , void* buf1_vbase , void* sts0_vaddr , void* sts1_vaddr ) ===
-This function initializes the chained buffer descriptors for the two source buffers and the frame buffer.
-The buf0 and buf1 user buffers must be large enough to store a complete image, and must be aligned on a 64 bytes boundary.
-The sts0 and sts1 user buffers contain just a Boolean, but they must be large enough to store 64 bytes, and must be aligned on a 64 bytes boundary.
- * '''buf0_vbase''' : virtual address of the first data buffer.
- * '''buf1_vbase''' : virtual address of  the second  data buffer,
- * '''sts0_vaddr''' : virtual address of the first buffer status.
- * '''sts1_vaddr''' : virtual address of the second buffer status.
-
- === 5) void '''giet_fbf_cma_start'''( unsigned int length ) ===
-This function activates the transfer of a stream of images from two user buffers to the frame buffer. It must be used in conjunction with the giet_fbf_cma_display() function. The chained buffer descriptors should have been initialized by the giet_fbf_cma_init_buf() function.
- * '''length''' is the size of the image (bytes). 
-
- === 6) void '''giet_fbf_cma_display'''( unsigned int buffer ) ===
-This function enables the transfer of the specified buffer.
- * '''buffer''' is the buffer index (0 or 1).
+ === 3) void '''giet_fbf_cma_alloc'''( unsigned int nbufs )
+This function allocates a private CMA channel  to the calling thread, and registers the channel index in the thread context. 
+The <nbufs> argument define the total number of chained user buffers. 
+As each user buffer contains one image, the buffer size must be FBUF_X_SIZE * FBUF_Y_SIZE.
+The user buffers can be distributed (one buffer per cluster) or not (all buffers in same cluster).
+This function initializes the chained buffer descriptor for the frame buffer (one single buffer).
+The thread exit if no CMA channel available.
+
+ === 4) void '''giet_fbf_cma_init_buf'''( unsigned int index  void* buf_vaddr , void* sts_vaddr ) ===
+This function initializes the chained buffer descriptor for one user buffer identified by the <index> argument.
+This <index> argument must be smaller than the <nbufs> argument in giet_fbf_cma_alloc() above.
+The set of user buffers will be transferred by the CMA peripheral in the order of increasing indexes.
+This function must be called <nbufs> times, to initialize the <nbufs> chained buffers descriptors. 
+Each user buffer must be large enough to store a complete image, and must be aligned on a 64 bytes boundary.
+The buffer status contain just a Boolean, but it must occupy 64 bytes, and must be aligned on a 64 bytes boundary.
+For a given user buffer, the buffer and the associated status must be in the same cluster.
+ * '''index''' : buffer index 
+ * '''buf_vaddr''' : virtual address of the user buffer.
+ * '''sts_vaddr''' : virtual address of the buffer status.
+The thread exit if buffers are not aligned, index too large, or buffer and status in different clusters.  
+
+ === 5) void '''giet_fbf_cma_start'''() ===
+This function activates the transfer of a stream of images from a set of chained user buffers to the frame buffer. It must be used in conjunction with the giet_fbf_cma_display() function. The chained buffer descriptors should have been initialized by the giet_fbf_cma_init_buf() function.
+
+ === 6) void '''giet_fbf_cma_display'''( unsigned int index ) ===
+This function enables the transfer of the buffer identified by the <index> argument.
+For each user buffer, the buffer status must be used as a SET/RESET synchronisation flip-flop, that is set by the application
+and reset by the CMA peripheral.  
 
  === 7) void '''giet_fbf_cma_stop'''( ) ===