fix cython, add pure pypy

Author: mattip

.gitignore

@@ -6,3 +6,6 @@
 main
 *.so
 .gdb_history
+build/
+c.raw
+pure_c.txt

create_fractal.c

@@ -1,9 +1,9 @@
-int mandel(float x, float y, int max_iters, unsigned int * val);
+int mandel(float x, float y, int max_iters, unsigned char * val);
 
 typedef struct _Img{
     int width;
     int height;
-    int * data;
+    unsigned char * data;
 } Img;
 
 
@@ -15,7 +15,7 @@ void create_fractal(Img img,  int iters) {
         int yy = y * img.width;
         for (int x=0; x < img.width; x++) {
             float real = x * pixel_size_x - 2;
-            unsigned int color;
+            unsigned char color;
             int ret = mandel(real, imag, iters, &color);
             img.data[yy + x] = color;
         }

create_fractal.h

@@ -0,0 +1,11 @@
+typedef struct _Img{
+    int width;
+    int height;
+    int * data;
+} cImg;
+
+
+
+int create_fractal(cImg img, int iters);
+int mandel(float real, float imag, int max_iters, unsigned char * val);
+

create_fractal.py

@@ -1,12 +1,59 @@
-from mandel import mandel
+#And for desert:
+import sys
+print(sys.executable)
+from timeit import default_timer as timer
+import cffi
+from PIL import Image
 
-def create_fractal(image, width, height, iters):
-    pixel_size_x = 3.0 / width
-    pixel_size_y = 2.0 / height
-    for y in range(height):
+ffi = cffi.FFI()
+
+class Img(object):
+    def __init__(self, width, height):
+        self.width = width
+        self.height = height
+        self.data = ffi.new('uint8_t[%d]' % (width*height,))
+
+def create_fractal(image, iters, func, oneval):
+    ''' Call a function for each pixel in the image, where
+        -2 < real < 1 over the columns and
+        -1 < imag < 1 over the rows
+    '''
+    pixel_size_x = 3.0 / image.width
+    pixel_size_y = 2.0 / image.height
+    for y in range(image.height):
         imag = y * pixel_size_y - 1
-        yy = y*width
-        for x in range(width):
+        yy = y * image.width
+        for x in range(image.width):
             real = x * pixel_size_x - 2
-            color = mandel(real, imag, iters)
-            image[yy+x] = color
+            func(real, imag, iters, oneval)
+            image.data[yy + x] = oneval[0]
+
+def mandel(x, y, max_iters, value):
+    """
+    Given the real and imaginary parts of a complex number,
+    determine if it is a candidate for membership in the Mandelbrot
+    set given a fixed number of iterations.
+    """
+    i = 0
+    c = complex(x,y)
+    z = 0.0j
+    for i in range(max_iters):
+        z = z*z + c
+        if (z.real*z.real + z.imag*z.imag) >= 4:
+            value[0] = i
+            return 0
+    value[0] = max_iters
+    return max_iters
+
+# Pure python
+width = 1500
+height = 1000
+image = Img(width, height)
+s = timer()
+oneval = ffi.new('uint8_t[1]')
+create_fractal(image, 20, mandel, oneval)
+e = timer()
+pure_pypy = e - s
+print('pure pypy required {:.2f} millisecs'.format(pure_pypy))
+im = Image.fromarray(image.data.reshape(height, width))
+im.save('pypyy.png')

main.c

@@ -1,5 +1,5 @@
 #include <stdio.h>
-#include <pgm.h>
+#include <stdlib.h>
 #include <time.h>
 
 // call this function to start a nanosecond-resolution timer
@@ -30,7 +30,8 @@ int main(int argc, const char *argv[], const char * env[])
     long time_elapsed_nanos;
     img.width = width;
     img.height = height;
-    img.data = (unsigned int*)malloc(width * height * sizeof(unsigned int));
+    size_t written;
+    img.data = (unsigned char*)malloc(width * height * sizeof(unsigned char));
     if (NULL == img.data)
         return -1;
 
@@ -39,12 +40,10 @@ int main(int argc, const char *argv[], const char * env[])
     time_elapsed_nanos = timer_end(vartime);
     fprintf(stdout, "create_fractal required %ld millisecs\n", time_elapsed_nanos / 1000000);
 
-    fid = fopen("c.pgm", "wb");
+    fid = fopen("c.raw", "wb");
     if (NULL == fid)
         return -2;
-    pgm_writepgminit(fid, width, height, 255, 0);
-    for (int i=0; i<height; i++)
-        pgm_writepgmrow(fid, img.data + width*i, width, 255, 0);
+    written = fwrite(img.data, sizeof(unsigned char), width * height, fid);
     fclose(fid);
     return 0;
 }

mandel.c

@@ -1,6 +1,6 @@
 #include <complex.h>
 
-int mandel(float x, float y, int max_iters, unsigned int * val)
+int mandel(float x, float y, int max_iters, unsigned char * val)
 {
     int i = 0;
     _Complex float c = CMPLX(x, y);