On Wed, Oct 18, 2006 at 12:44:30AM -0600, Grant Grundler wrote: > And I've fixed the algorithm to handle 32-bit extracts in the test > below and will submit the same code in the next patch.
Greg, Previous patch broke extract/implement for 32-bit report fields. Adam Kropelin had posted 32-bit fix in June 2005 about two weeks after I originally had posted my fixes for big endian support. Adam has a UPS device which reports LINEV using 32-bits. Added comments to describe the limitations of the code. extract() is the same version I posted earlier and tested in user space. Made similar changes to implement() routine. I've written (and will shortly post) a test for implement(). Code tested on C3600 (parisc) with USB keyboard/mouse attached. Signed-off-by: Grant Grundler <[EMAIL PROTECTED]> diff --git a/drivers/usb/input/hid-core.c b/drivers/usb/input/hid-core.c index 45f44fe..1aada46 100644 --- a/drivers/usb/input/hid-core.c +++ b/drivers/usb/input/hid-core.c @@ -751,30 +751,55 @@ static __inline__ __u32 s32ton(__s32 val /* * Extract/implement a data field from/to a little endian report (bit array). + * + * Code sort-of follows HID spec: + * http://www.usb.org/developers/devclass_docs/HID1_11.pdf + * + * While the USB HID spec allows unlimited length bit fields in "report + * descriptors", most devices never use more than 16 bits. + * One model of UPS is claimed to report "LINEV" as a 32-bit field. + * Search linux-kernel and linux-usb-devel archives for "hid-core extract". */ static __inline__ __u32 extract(__u8 *report, unsigned offset, unsigned n) { - u32 x; + u64 x; + + WARN_ON(n > 32); report += offset >> 3; /* adjust byte index */ - offset &= 8 - 1; - x = get_unaligned((u32 *) report); - x = le32_to_cpu(x); - x = (x >> offset) & ((1 << n) - 1); - return x; + offset &= 7; /* now only need bit offset into one byte */ + x = get_unaligned((u64 *) report); + x = le64_to_cpu(x); + x = (x >> offset) & ((1ULL << n) - 1); /* extract bit field */ + return (u32) x; } +/* + * "implement" : set bits in a little endian bit stream. + * Same concepts as "extract" (see comments above). + * The data mangled in the bit stream remains in little endian + * order the whole time. It make more sense to talk about + * endianness of register values by considering a register + * a "cached" copy of the little endiad bit stream. + */ static __inline__ void implement(__u8 *report, unsigned offset, unsigned n, __u32 value) { - u32 x; + u64 x; + u64 m = (1ULL << n) - 1; + + WARN_ON(n > 32); + + WARN_ON(value > m); + value &= m; report += offset >> 3; - offset &= 8 - 1; - x = get_unaligned((u32 *)report); - x &= cpu_to_le32(~((((__u32) 1 << n) - 1) << offset)); - x |= cpu_to_le32(value << offset); - put_unaligned(x,(u32 *)report); + offset &= 7; + + x = get_unaligned((u64 *)report); + x &= cpu_to_le64(~(m << offset)); + x |= cpu_to_le64(((u64) value) << offset); + put_unaligned(x, (u64 *) report); } /* ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
