""" Cast Copy Tranpose is used in Numeric's LinearAlgebra.py to convert
    C ordered arrays to Fortran order arrays before calling Fortran
    functions.  A couple of C implementations are provided here that 
    show modest speed improvements.  One is an "inplace" transpose that
    does an in memory transpose of an arrays elements.  This is the
    fastest approach and is beneficial if you don't need to keep the
    original array.    
"""
# C:\home\ej\wrk\scipy\compiler\examples>python cast_copy_transpose.py
# Cast/Copy/Transposing (150,150)array 1 times
#  speed in python: 0.870999932289
#  speed in c: 0.25
#  speed up: 3.48
#  inplace transpose c: 0.129999995232
#  speed up: 6.70

import Numeric
from Numeric import *
import sys
sys.path.insert(0,'..')
import inline_tools
import c_spec
from converters import blitz as cblitz

def _cast_copy_transpose(type,a_2d):
    assert(len(shape(a_2d)) == 2)
    new_array = zeros(shape(a_2d),type)
    code = """
           for(int i = 0; i < Na_2d[0]; i++)
               for(int j = 0; j < Na_2d[1]; j++)
                   new_array(i,j) = a_2d(j,i);  
           """ 
    inline_tools.inline(code,['new_array','a_2d'],
                        type_converters = cblitz,
                        compiler='gcc',
                        verbose = 1)
    return new_array

def _cast_copy_transpose2(type,a_2d):
    assert(len(shape(a_2d)) == 2)
    new_array = zeros(shape(a_2d),type)
    code = """
           const int I = Na_2d[0];
           const int J = Na_2d[1];
           for(int i = 0; i < I; i++)
           {
               int new_off = i*J;
               int old_off = i;
               for(int j = 0; j < J; j++)
               {
                   new_array[new_off++] = a_2d[old_off];
                   old_off += I; 
               }    
           } 
           """ 
    inline_tools.inline(code,['new_array','a_2d'],compiler='gcc',verbose=1)
    return new_array

def _inplace_transpose(a_2d):
    assert(len(shape(a_2d)) == 2)
    numeric_type = c_spec.num_to_c_types[a_2d.typecode()]
    code = """
           %s temp;
           for(int i = 0; i < Na_2d[0]; i++)
               for(int j = 0; j < Na_2d[1]; j++)
               {
                   temp = a_2d(i,j);
                   a_2d(i,j) = a_2d(j,i);
                   a_2d(j,i) = temp; 
               }     
           """ % numeric_type
    inline_tools.inline(code,['a_2d'],
                        type_converters = cblitz,
                        compiler='gcc',
                        extra_compile_args = ['-funroll-all-loops'],
                        verbose =2 )
    return a_2d
    #assert(len(shape(a_2d)) == 2)
    #type = a_2d.typecode()
    #new_array = zeros(shape(a_2d),type)
    ##trans_a_2d = transpose(a_2d)
    #numeric_type = c_spec.num_to_c_types[type]
    #code = """
    #       for(int i = 0; i < Na_2d[0]; i++)
    #           for(int j = 0; j < Na_2d[1]; j++)
    #               new_array(i,j) = (%s) a_2d(j,i);
    #       """ % numeric_type
    #inline_tools.inline(code,['new_array','a_2d'],
    #                    type_converters = cblitz,
    #                    compiler='gcc',
    #                    verbose = 1)
    #return new_array

def cast_copy_transpose(type,*arrays):
    results = []
    for a in arrays:
        results.append(_cast_copy_transpose(type,a))
    if len(results) == 1:
        return results[0]
    else:
        return results

def cast_copy_transpose2(type,*arrays):
    results = []
    for a in arrays:
        results.append(_cast_copy_transpose2(type,a))
    if len(results) == 1:
        return results[0]
    else:
        return results

def inplace_cast_copy_transpose(*arrays):
    results = []
    for a in arrays:
        results.append(_inplace_transpose(a))
    if len(results) == 1:
        return results[0]
    else:
        return results

def _castCopyAndTranspose(type, *arrays):
    cast_arrays = ()
    for a in arrays:
        if a.typecode() == type:
            cast_arrays = cast_arrays + (copy.copy(Numeric.transpose(a)),)
        else:
            cast_arrays = cast_arrays + (copy.copy(
                                       Numeric.transpose(a).astype(type)),)
    if len(cast_arrays) == 1:
            return cast_arrays[0]
    else:
        return cast_arrays

import time


def compare(m,n):
    a = ones((n,n),Float64)
    type = Float32
    print 'Cast/Copy/Transposing (%d,%d)array %d times' % (n,n,m)
    t1 = time.time()
    for i in range(m):
        for i in range(n):
            b = _castCopyAndTranspose(type,a)
    t2 = time.time()
    py = (t2-t1)
    print ' speed in python:', (t2 - t1)/m
    

    # load into cache    
    b = cast_copy_transpose(type,a)
    t1 = time.time()
    for i in range(m):
        for i in range(n):
            b = cast_copy_transpose(type,a)
    t2 = time.time()
    print ' speed in c (blitz):',(t2 - t1)/ m    
    print ' speed up   (blitz): %3.2f' % (py/(t2-t1))

    # load into cache    
    b = cast_copy_transpose2(type,a)
    t1 = time.time()
    for i in range(m):
        for i in range(n):
            b = cast_copy_transpose2(type,a)
    t2 = time.time()
    print ' speed in c (pointers):',(t2 - t1)/ m    
    print ' speed up   (pointers): %3.2f' % (py/(t2-t1))

    # inplace tranpose
    b = _inplace_transpose(a)
    t1 = time.time()
    for i in range(m):
        for i in range(n):
            b = _inplace_transpose(a)
    t2 = time.time()
    print ' inplace transpose c:',(t2 - t1)/ m    
    print ' speed up: %3.2f' % (py/(t2-t1))
    
if __name__ == "__main__":
    m,n = 1,500
    compare(m,n)