abidrahmank

Exposing raw C++ buffers as NumPy arrays using Pybind11

Sometimes you have to work with C++ libraries that use raw pointers and arrays that you need to have access to from python. Indeed, working with C styles arrays is sometimes considered bad practice but many people still do...

The solution here is for the C++ side to provide the raw memory address of the data buffer, and then use numpy's array interface mechanism to create an ndarray that uses this buffer.

This allows the user to view and change elements of the buffers with no copies in a way that is visible to both C++ and Python sides.

abidrahmank

{0: 'tench, Tinca tinca',
 1: 'goldfish, Carassius auratus',
 2: 'great white shark, white shark, man-eater, man-eating shark, Carcharodon carcharias',
 3: 'tiger shark, Galeocerdo cuvieri',
 4: 'hammerhead, hammerhead shark',
 5: 'electric ray, crampfish, numbfish, torpedo',
 6: 'stingray',
 7: 'cock',
 8: 'hen',
 9: 'ostrich, Struthio camelus',

abidrahmank

abidrahmank

#include <stdio.h>
int square(int x);
int cube(int x);
void map(int, int, int func(int));

int main(){
    map(1,5,square);
    map(1,5,cube);    

}

abidrahmank

#include <stdio.h>

typedef unsigned int uint;

__global__ void square(uint *d_out, uint *d_in, int rows){
    int loc = blockIdx.x*rows + 2*threadIdx.x;
	int f = d_in[loc]+d_in[loc+1];
	d_out[loc/2] = f*f;
//	printf("%d %f %f %f %f %f \n", loc, d_in[loc], d_in[loc+1], f, temp, d_out[loc/2]);
	}

abidrahmank

#include <stdio.h>

__global__ void kernel(unsigned char* d_in, unsigned char* d_out){
    int idx = blockIdx.x;
	int idy = threadIdx.x;
	
	int gray_adr = idx*64 + idy;    // calculating address for writing grayscale value
	int clr_adr = 3*gray_adr;       // calculating address for reading RGB values

	if(gray_adr<(64*64))

abidrahmank

#include <opencv2/core/core.hpp>
#include <opencv2/core/utility.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
#include <stdio.h>
#include <cuda.h>
#include <cuda_runtime.h>

using namespace std;
using namespace cv;

abidrahmank

UNKNOWN DEZIRE

SYSTEM (Android 4.0.4)
	Model: Dezire
	Manufacturer: unknown
	Device: nuclear-evb
	Product: nuclear_evb
	Brand: softwinners
	Android Version: 4.0.4 (Ice Cream Sandwich)
	API Level: 15

abidrahmank

[    22.904] 
X.Org X Server 1.13.3
Release Date: 2013-03-07
[    22.904] X Protocol Version 11, Revision 0
[    22.904] Build Operating System:  2.6.32-358.2.1.el6.x86_64 
[    22.904] Current Operating System: Linux localhost.localdomain 3.10.11-100.fc18.x86_64 #1 SMP Mon Sep 9 13:06:31 UTC 2013 x86_64
[    22.904] Kernel command line: BOOT_IMAGE=/vmlinuz-3.10.11-100.fc18.x86_64 root=UUID=21e9312d-15f0-4a51-99a6-446bfab1c7e4 ro rd.md=0 rd.lvm=0 rd.dm=0 rd.luks=0 vconsole.keymap=us rhgb quiet LANG=en_US.UTF-8 nouveau.modeset=0 rd.driver.blacklist=nouveau
[    22.904] Build Date: 17 April 2013  04:51:09AM
[    22.904] Build ID: xorg-x11-server 1.13.3-3.fc18 
[    22.904] Current version of pixman: 0.28.0

abidrahmank

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 310.51  (buildmeister@swio-display-x86-rhel47-04)  Wed May  1 18:10:19 PDT 2013

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection