ChangeSet 1.842.46.16, 2002/11/27 09:54:32-08:00, jtyner@cs.ucr.edu
[PATCH] [patch] speed/clean up vicam_decode_color
This patch cleans up the vicam_decode_color function by removing
unused/useless variables and combining the two "x" loops inside the
y loop into one. It also reduces the number of times that the "x"
loop occurs from 512 to 320 which should provide a decent speed
increase. It also fixes a bug in the y loop that wrote beyond its bound.
diff -Nru a/drivers/usb/media/vicam.c b/drivers/usb/media/vicam.c
--- a/drivers/usb/media/vicam.c Wed Nov 27 12:49:22 2002
+++ b/drivers/usb/media/vicam.c Wed Nov 27 12:49:22 2002
@@ -51,19 +51,25 @@
#define DBG(fmn,args...) do {} while(0)
#endif
-/* Version Information */
-#define DRIVER_VERSION "v1.0"
-#define DRIVER_AUTHOR "Joe Burks, jburks@wavicle.org"
-#define DRIVER_DESC "ViCam WebCam Driver"
+#define DRIVER_AUTHOR "Joe Burks, jburks@wavicle.org"
+#define DRIVER_DESC "ViCam WebCam Driver"
/* Define these values to match your device */
#define USB_VICAM_VENDOR_ID 0x04c1
#define USB_VICAM_PRODUCT_ID 0x009d
-#define VICAM_BYTES_PER_PIXEL 3
-#define VICAM_MAX_READ_SIZE (512*242+128)
-#define VICAM_MAX_FRAME_SIZE (VICAM_BYTES_PER_PIXEL*320*240)
-#define VICAM_FRAMES 2
+#define VICAM_BYTES_PER_PIXEL 3
+#define VICAM_MAX_READ_SIZE (512*242+128)
+#define VICAM_MAX_FRAME_SIZE (VICAM_BYTES_PER_PIXEL*320*240)
+#define VICAM_FRAMES 2
+
+#define VICAM_HEADER_SIZE 64
+
+#define clamp( x, l, h ) max_t( __typeof__( x ), \
+ ( l ), \
+ min_t( __typeof__( x ), \
+ ( h ), \
+ ( x ) ) )
/* Not sure what all the bytes in these char
* arrays do, but they're necessary to make
@@ -425,7 +431,7 @@
static int vicam_probe( struct usb_interface *intf, const struct usb_device_id *id);
static void vicam_disconnect(struct usb_interface *intf);
static void read_frame(struct vicam_camera *cam, int framenum);
-static void vicam_decode_color( char *data, char *rgb);
+static void vicam_decode_color(const u8 *, u8 *);
static int __send_control_msg(struct vicam_camera *cam,
u8 request,
@@ -840,106 +846,75 @@
return 0;
}
-inline int pin(int x)
+static void vicam_decode_color(const u8 *data, u8 *rgb)
{
- return((x > 255) ? 255 : ((x < 0) ? 0 : x));
-}
+ /* vicam_decode_color - Convert from Vicam Y-Cr-Cb to RGB
+ * Copyright (C) 2002 Monroe Williams (monroe@pobox.com)
+ */
-inline void writepixel(char *rgb, int Y, int Cr, int Cb)
-{
- Y = 1160 * (Y - 16);
-
- rgb[2] = pin( ( ( Y + ( 1594 * Cr ) ) + 500 ) / 1300 );
- rgb[1] = pin( ( ( Y - ( 392 * Cb ) - ( 813 * Cr ) ) + 500 ) / 1000 );
- rgb[0] = pin( ( ( Y + ( 2017 * Cb ) ) + 500 ) / 900 );
-}
-
-#define DATA_HEADER_SIZE 64
-
-// --------------------------------------------------------------------------------
-// vicam_decode_color - Convert from Vicam Y-Cr-Cb to RGB
-//
-// Copyright (C) 2002 Monroe Williams (monroe@pobox.com)
-// --------------------------------------------------------------------------------
-
-static void vicam_decode_color( char *data, char *rgb)
-{
- int x,y;
- int Cr, Cb;
- int sign;
- int prevX, nextX, prevY, nextY;
- int skip;
- unsigned char *src;
- unsigned char *dst;
+ int i, prevY, nextY;
prevY = 512;
nextY = 512;
- src = data + DATA_HEADER_SIZE;
- dst = rgb;
-
- for(y = 1; y < 241; y += 2)
- {
- // even line
- sign = 1;
- prevX = 1;
- nextX = 1;
-
- skip = 0;
-
- dst = rgb + (y-1)*320*3;
-
- for(x = 0; x < 512; x++)
- {
- if(x == 512-1)
- nextX = -1;
+ data += VICAM_HEADER_SIZE;
- Cr = sign * ((src[prevX] - src[0]) + (src[nextX] - src[0])) >> 1;
- Cb = sign * ((src[prevY] - src[prevX + prevY]) + (src[prevY] - src[nextX + prevY]) + (src[nextY] - src[prevX + nextY]) + (src[nextY] - src[nextX + nextY])) >> 2;
+ for( i = 0; i < 240; i++, data += 512 ) {
+ const int y = ( i * 242 ) / 240;
- writepixel(
- dst + ((x*5)>>3)*3,
- src[0] + (sign * (Cr >> 1)),
- Cr,
- Cb);
-
- src++;
- sign *= -1;
- prevX = -1;
- }
+ int j, prevX, nextX;
+ int Y, Cr, Cb;
- prevY = -512;
-
- if(y == (242 - 2))
+ if ( y == 242 - 1 ) {
nextY = -512;
+ }
- // odd line
- sign = 1;
prevX = 1;
nextX = 1;
- skip = 0;
+ for ( j = 0; j < 320; j++, rgb += 3 ) {
+ const int x = ( j * 512 ) / 320;
+ const u8 * const src = &data[x];
- dst = rgb + (y)*320*3;
-
- for(x = 0; x < 512; x++)
- {
- if(x == 512-1)
+ if ( x == 512 - 1 ) {
nextX = -1;
-
- Cr = sign * ((src[prevX + prevY] - src[prevY]) + (src[nextX + prevY] - src[prevY]) + (src[prevX + nextY] - src[nextY]) + (src[nextX + nextY] - src[nextY])) >> 2;
- Cb = sign * ((src[0] - src[prevX]) + (src[0] - src[nextX])) >> 1;
+ }
- writepixel(
- dst + ((x * 5)>>3)*3,
- src[0] - (sign * (Cb >> 1)),
- Cr,
- Cb);
+ Cr = ( src[prevX] - src[0] ) +
+ ( src[nextX] - src[0] );
+ Cr /= 2;
+
+ Cb = ( src[prevY] - src[prevX + prevY] ) +
+ ( src[prevY] - src[nextX + prevY] ) +
+ ( src[nextY] - src[prevX + nextY] ) +
+ ( src[nextY] - src[nextX + nextY] );
+ Cb /= 4;
+
+ Y = 1160 * ( src[0] + ( Cr / 2 ) - 16 );
+
+ if ( i & 1 ) {
+ int Ct = Cr;
+ Cr = Cb;
+ Cb = Ct;
+ }
+
+ if ( ( x ^ i ) & 1 ) {
+ Cr = -Cr;
+ Cb = -Cb;
+ }
+
+ rgb[0] = clamp( ( ( Y + ( 2017 * Cb ) ) +
+ 500 ) / 900, 0, 255 );
+ rgb[1] = clamp( ( ( Y - ( 392 * Cb ) -
+ ( 813 * Cr ) ) +
+ 500 ) / 1000, 0, 255 );
+ rgb[2] = clamp( ( ( Y + ( 1594 * Cr ) ) +
+ 500 ) / 1300, 0, 255 );
- src++;
- sign *= -1;
prevX = -1;
}
+
+ prevY = -512;
}
}
@@ -1030,7 +1005,6 @@
vicam_decode_color(cam->raw_image,
cam->framebuf +
0 * VICAM_MAX_FRAME_SIZE);
-
}
count = min_t(size_t, count, VICAM_MAX_FRAME_SIZE - *ppos);