On Wed, 27 Feb 2008, Karol Kozimor wrote: > On 26-02-2008, at 21:42, Julia Lawall wrote: > > if (invert) /* invert target value */ > > - led_out = !led_out & 0x1; > > + led_out = !(led_out & 0x1); > > > > if (!write_acpi_int(hotk->handle, ledname, led_out, NULL)) > > printk(KERN_WARNING "Asus ACPI: LED (%s) write failed\n", > > > IIRC we're just supposed to flip the last bit here, so the original > code is correct. I spent some time thinking about this one. The original code is ok if led_out is always either 0x01 or 0x00. But what if it is eg 0xc0? Then the negation amounts to the negation of a nonzero number, so the result is 0. So the result of the bit and is 0. So the last bit is not flipped. But I don't know what is the range of led_out. If it is always 1 or 0, then why bother with the bit and? julia - To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
