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电梯直达

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发表于 2008-03-30 10:15 |只看该作者 |倒序浏览

下面这个是本人写的源码,刚学python不久,请见谅.欢迎大侠指点.
下面代码中黑体字的那两层loop循环,xres是240,yres是320,循环中间实际上就是从二进制文件中读取数据,处理一下,再写入一个文件里面.
但是这样的代码,运行起来速度难以接受,居然需要二十秒左右的时间,这个代码是在arm上运行的,cpu时钟是312M.同样差不多的c代码,1s之内
就能搞定,这难道就是传说中的python的性能问题吗?谢谢各位了.

#!/sdcard/Documents/sdcard/python2.5.2/bin/python2.5
import os,fcntl
from ctypes import *
from mmap import mmap,PROT_READ,PROT_WRITE,MAP_SHARED
from struct import unpack,pack
from array import array
class _fb_bitfield(Structure):
_fields_=[ ('offset',  c_ulong),
('length',  c_ulong),
('msb_right',  c_ulong) ]
class _fb_var_screeninfo(Structure):
_fields_=[ ('xres',  c_ulong), #visible resolution
('yres',  c_ulong),
('xres_virtual', c_ulong),
('yres_virtual', c_ulong),
('xoffset',  c_ulong),
('yoffset',  c_ulong),
('bits_per_pixel', c_ulong),
('grayscale',  c_ulong),

('red', _fb_bitfield),
('green',  _fb_bitfield),
('blue',             _fb_bitfield),
('transp',  _fb_bitfield),
('nonstd',  c_ulong),
('activate',  c_ulong),
('height',  c_ulong),
('weight',  c_ulong),
('accel_flags',  c_ulong),
('pixclock',  c_ulong)
]

class _fb_fix_screeninfo(Structure):
_fields_=[ ('id[0]',  c_char), ('id[1]',  c_char),('id[2]',  c_char),('id[3]',  c_char),
   ('id[4]',  c_char),('id[5]',  c_char),('id[6]',  c_char),('id[7]',  c_char),
   ('id[8]',  c_char),('id[9]',  c_char),('id[10]',  c_char),('id[11]',  c_char),
   ('id[12]',  c_char),('id[13]',  c_char),('id[14]',  c_char),('id[15]',  c_char),
('smem_start',  c_ulong),
('smem_len',  c_ulong)
]

ioctl_name={'FBIOGET_VSCREENINFO':0x4600,
      'FBIOGET_FSCREENINFO':0x4602}

bmp_header=array('B',[0x42, 0x4D, 0x36, 0x84, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x36, 0x00, 0x00, 0x00, 0x28, 0x00,
  0x00, 0x00, 0xF0, 0x00, 0x00, 0x00, 0x40, 0x01, 0x00, 0x00, 0x01, 0x00, 0x18, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x84, 0x03, 0x00, 0xC4, 0x0E, 0x00, 0x00, 0xC4, 0x0E, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00])
class fb0_func():
def __init__(self):
  fd=os.open('/dev/fb0',os.O_RDWR)
  var=_fb_var_screeninfo()
  err=fcntl.ioctl(fd,ioctl_name['FBIOGET_VSCREENINFO'],var,1)
  fix=_fb_fix_screeninfo()
  err=fcntl.ioctl(fd,ioctl_name['FBIOGET_FSCREENINFO'],fix,1)
  os.close(fd)
  self.xres=var.xres
  self.yres=var.yres
  self.smem_len=fix.smem_len
  #print "xres:%d" % self.xres
  #print "yres:%d" % self.yres
  #print "smem_len:%d" % self.smem_len

def dump(self):
  fd=os.open('/dev/fb0',os.O_RDWR)
  map=mmap(fd, self.smem_len,MAP_SHARED,PROT_READ | PROT_WRITE)
fd_dumpfb0=open('fb0.dat','wb+')
  fd_dumpfb0.write(map)
  fd_dumpfb0.close()
  os.close(fd)

def snap(self):
  fd=os.open('/dev/fb0',os.O_RDWR)
  fd_snapfb0=open('fb0.bmp','wb+')

  #write bmp header
  fd_snapfb0.write(bmp_header)

  #write RGB data
  map=mmap(fd, self.smem_len,MAP_SHARED,PROT_READ | PROT_WRITE)
  xres=self.xres
  yres=self.yres
  for x in range(1,xres):
   for y in range(1,yres):
   #pp=2*(x+y*xres)
   data=map.read(2)
   s1,s2=unpack('2B',data[:])
   #print "%s %s" % (hex(s1),hex(s2))
   r = ((s1&0x1f) << 3);
   g = ((s2&0x7) << 5) | ((s1&0xe0) >> 3);
   b = ((s2&0xf );
   #print "%d %d %d" % (r,g,b)
   bmpdata=pack("3B",r,g,b)
   fd_snapfb0.write(bmpdata)
  fd_snapfb0.close()
  os.close(fd)

def profile_test():
a=fb0_func()
a.dump()
a.snap()

if __name__ == "__main__":
import profile
profile.run("profile_test()"