Changes between Version 20 and Version 21 of user_applications

Timestamp:

Jan 19, 2016, 1:58:30 PM (8 years ago)

Author:

alain

Comment:

--

user_applications

@@ -57 +57 @@
 pthread_join() function to detect application completion. All others threads are executing the execute() function. Each execute() function is handling exactly (image_size / nthreads) lines.
 
-The input and output buffers containing the source and transposed images are allocated from the user heap distributed in all clusters. There is (image size / clusters) lines per cluster. Therefore, the data read are mostly local, but the data write are mostly remote.
-
-The number of clusters  must be a power of 2 no larger than 256.
-The number of processors per cluster must be a power of 2 no larger than 4.
+The buf_in[x,y] and buf_out[x,y] buffers containing the direct ans transposed images are distributed in clusters:
+In each cluster[x,y], the thread running on processor P[x,y,0] uses the giet_fat_mmap() function to map the buf_in[x,y] and buf_out[x,y] buffers containing a set of lines.
+Then, all threads in cluster[x,y] read pixels from the local buf_in[x,y] buffer, and write the pixels to the remote buf_out[x,y] buffers. Finally, each thread display
+a part of the transposed image to the frame buffer. There is (image size / clusters) lines per cluster. Therefore, the data read are local, but the data write are mostly remote.
+
+ * The image size must fit the frame buffer width and height, that must be power of 2.
+ * The number of clusters  must be a power of 2 no larger than 256.
+ * The number of processors per cluster must be a power of 2 no larger than 4.
+ * The number of clusters cannot be larger than (image_size * image_size) / 4096, because the size of buf_in[x,y] and buf_out[x,y] must be multiple of 4096.
 
 It requires one TTY terminal, shared by all threads.
 
 The source code can be found [source:soft/giet_vm/applications/transpose/transpose.c here], and the mapping is defined  [source:soft/giet_vm/applications/transpose/transpose.py here].
+
+The [source:soft/giet_vm_applications/transpose/transpose_rw.c transpose.c] file contains a variant that use the giet_fat_read() and giet_fat_write() system calls, to access the files.
 
 == __convol__ ==