From ec67ac9af1c9a02130347c4ed6f32fa03f55eba2 Mon Sep 17 00:00:00 2001
From: Thomas Grill <xovo@users.sourceforge.net>
Date: Thu, 10 Mar 2005 04:59:00 +0000
Subject: more buffer functionality (support sequence and number protocols)
 more examples preset sys.argv for module loading support for buffer objects
 (preliminary)

svn path=/trunk/; revision=2615
---
 externals/grill/py/scripts/buffer.py | 50 +++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 18 deletions(-)

(limited to 'externals/grill/py/scripts/buffer.py')

diff --git a/externals/grill/py/scripts/buffer.py b/externals/grill/py/scripts/buffer.py
index 4c81caab..19b6f5d3 100644
--- a/externals/grill/py/scripts/buffer.py
+++ b/externals/grill/py/scripts/buffer.py
@@ -7,12 +7,9 @@
 
 """This is an example script for the py/pyext object's buffer support.
 
-PD/Max buffers can be imported to and exported from numarray arrays.
+PD/Max buffers can be mapped to numarray arrays.
 For numarray see http://numeric.scipy.org
-It will probably once be replaced by Numeric
-
-- _import(buffer): copy contents from the buffer to a new numarray object
-- _export(buffer,numarray): export contents of numarray object to the buffer
+It will probably once be replaced by Numeric(3)
 """
 
 import sys
@@ -20,7 +17,7 @@ import sys
 try:
     import pyext
 except:
-    print "ERROR: This script must be loaded by the PD/Max pyext external"
+    print "ERROR: This script must be loaded by the PD/Max py/pyext external"
 
 try:    
     from numarray import *
@@ -28,19 +25,36 @@ except:
     print "Failed importing numarray module:",sys.exc_value
 
 def mul(*args):
+    # create buffer objects
+    # as long as these variables live the underlying buffers are locked
     c = pyext.Buffer(args[0])
-    dst = c.array()
-    dst[:] = 0
-    a = pyext.Buffer(args[1]).array()
-    b = pyext.Buffer(args[2]).array()
-    dst += a*b
-    c.dirty()   
+    a = pyext.Buffer(args[1])
+    b = pyext.Buffer(args[2])
+
+    # slicing causes numarrays (mapped to buffers) to be created
+    # note the c[:] - to assign contents you must assign to a slice of the buffer
+    c[:] = a[:]*b[:]  
 
 def add(*args):
     c = pyext.Buffer(args[0])
-    dst = c.array()
-    dst[:] = 0
-    a = pyext.Buffer(args[1]).array()
-    b = pyext.Buffer(args[2]).array()
-    dst += a+b
-    c.dirty()   
+    a = pyext.Buffer(args[1])
+    b = pyext.Buffer(args[2])
+
+    # this is also possible, but is probably slower
+    # the + converts a into a numarray, the argument b is taken as a sequence
+    # depending on the implementation in numarray this may be as fast
+    # as above or not
+    c[:] = a+b  
+
+def fadein(target):
+    a = pyext.Buffer(target)
+    # in place operations are ok
+    a *= arange(len(a),type=Float32)/len(a)
+
+def neg(target):
+    a = pyext.Buffer(target)
+    # in place transformation (see numarray ufuncs)
+    negative(a[:],a[:])
+    # must mark buffer content as dirty to update graph
+    # (no explicit assignment occurred)
+    a.dirty() 
-- 
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