Changes between Version 126 and Version 127 of library_stdio

Timestamp:

Oct 6, 2015, 11:41:10 AM (9 years ago)

Author:

alain

Comment:

--

library_stdio

@@ -403 +403 @@
  == __Frame Buffer related system calls__ ==
 
-To display images, an user thread can access the frame buffer through a memcpy() or through the ''Chained Buffer DMA'' controller (called CMA). 
-The four first functions use a private CMA channel that is registered in the thread context. The Two last functions use a memcpy().
-
- === 1) void '''giet_fbf_cma_alloc'''()
+To display images, an user application must get the frame buffer ownership, and check the frame buffer size (width and height). 
+Then, it can access the frame buffer through a (software) memcpy() or through the (hardware) ''Chained Buffer DMA'' controller (called CMA). 
+
+ === 1) void '''giet_fbf_size'''( unsigned int* width , unsigned int* height) ===
+This function returns in the <width> and <height> arguments the number of pixels per line, and the number of lines of the frame buffer
+
+ === 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 lock is released when the thread completes execution, after a giet_pthread_exit(), or a get_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
 
- === 2) void '''giet_fbf_cma_init_buf'''( void* buf0_vbase , void* buf1_vbase , void* sts0_vaddr , void* sts1_vaddr ) ===
+ === 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.
@@ -420 +427 @@
  * '''sts1_vaddr''' : virtual address of the second buffer status.
 
- === 3) void '''giet_fbf_cma_start'''( unsigned int length ) ===
+ === 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). 
 
- === 4) void '''giet_fbf_cma_display'''( unsigned int buffer ) ===
+ === 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).
 
- === 5) void '''giet_fbf_cma_stop'''( ) ===
+ === 7) void '''giet_fbf_cma_stop'''( ) ===
 This function desactivates the CMA channel allocated to the calling thread.
 
- === 6) void '''giet_fbf_sync_read'''( unsigned int offset , void* buffer , unsigned int length ) ===
+ === 8) void '''giet_fbf_sync_read'''( unsigned int offset , void* buffer , unsigned int length ) ===
 This blocking function use a memcopy strategy to transfer data from the frame buffer to an user buffer.
  * '''offset''' defines the offset (in bytes) in the frame buffer,
@@ -437 +444 @@
  * '''length'''  is the number of bytes to be transfered. 
 
- === 7) void '''giet_fbf_sync_write'''( unsigned int offset , void* buffer , unsigned int length ) ===
+ === 9) void '''giet_fbf_sync_write'''( unsigned int offset , void* buffer , unsigned int length ) ===
 This blocking function use a memcopy strategy to transfer data from an user buffer to the frame buffer.
  * '''offset''' defines the offset (in bytes) in the frame buffer,