V4L/DVB (5517): Usbvision: store the device database more efficiently
One bit wide bitfields need to declared unsigned to have the range 0 to
1, or they have the range -1 to 0.
A few techniques to reduce the driver's size by about 1700 bytes on ia32,
probably more on x86-64.
Put the biggest fields first, less padding is necessary that way.
Put fields with a limited range into a smaller type. For example
VideoChannels will fit in 3 bits, and TunerType can use 8 bits.
Vin_Reg1, Vin_Reg2, and Dvi_yuv define values for 8-bit registers, but
they can't just go into an 8-bit field with no changes, since -1 was used
as a flag to indicate a value was not present. So what we do is create a
one-bit flag for each one to indicate if a value is or is not present.
This only takes 9 bits and has the added advantage that when the register
isn't overridden (Vin_Reg[12] never are) it doesn't need to appear in the
structure definition since the default value for the flag will be zero.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Acked-by: Thierry MERLE <thierry.merle@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/usbvision/usbvision.h b/drivers/media/video/usbvision/usbvision.h
index b4412a5..9cad777 100644
--- a/drivers/media/video/usbvision/usbvision.h
+++ b/drivers/media/video/usbvision/usbvision.h
@@ -342,21 +342,24 @@
#define BRIDGE_NT1005 1005
struct usbvision_device_data_st {
- int Interface; /* to handle special interface number like BELKIN and Hauppauge WinTV-USB II */
- int Codec;
- int VideoChannels;
__u64 VideoNorm;
- int AudioChannels;
- int Radio:1;
- int vbi:1;
- int Tuner:1;
- int TunerType;
- int Vin_Reg1;
- int Vin_Reg2;
- int X_Offset;
- int Y_Offset;
- int Dvi_yuv;
- char *ModelString;
+ const char *ModelString;
+ int Interface; /* to handle special interface number like BELKIN and Hauppauge WinTV-USB II */
+ __u16 Codec;
+ unsigned VideoChannels:3;
+ unsigned AudioChannels:2;
+ unsigned Radio:1;
+ unsigned vbi:1;
+ unsigned Tuner:1;
+ unsigned Vin_Reg1_override:1; /* Override default value with */
+ unsigned Vin_Reg2_override:1; /* Vin_Reg1, Vin_Reg2, etc. */
+ unsigned Dvi_yuv_override:1;
+ __u8 Vin_Reg1;
+ __u8 Vin_Reg2;
+ __u8 Dvi_yuv;
+ __u8 TunerType;
+ __s16 X_Offset;
+ __s16 Y_Offset;
};
/* Declared on usbvision-cards.c */