From 95d1c8951e5bd50bb89654a99a7012b1e75646bd Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Wed, 6 Apr 2016 10:19:58 -0700 Subject: HID: simplify implement() a bit The 'size' variable is not really needed, and we can also shift constant in the loop body when masking off existing bits. Also we do not have to use 64 bit calculations if we take an extra branch. [jkosina@suse.cz: fix a small error in changelog] Suggested-by: Doug Anderson Signed-off-by: Dmitry Torokhov Reviewed-by: Douglas Anderson Signed-off-by: Jiri Kosina --- drivers/hid/hid-core.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) (limited to 'drivers/hid') diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index bdb8cc8..9985c0a 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1129,49 +1129,46 @@ EXPORT_SYMBOL_GPL(hid_field_extract); static void __implement(u8 *report, unsigned offset, int n, u32 value) { unsigned int idx = offset / 8; - unsigned int size = offset + n; unsigned int bit_shift = offset % 8; int bits_to_set = 8 - bit_shift; - u8 bit_mask = 0xff << bit_shift; while (n - bits_to_set >= 0) { - report[idx] &= ~bit_mask; + report[idx] &= ~(0xff << bit_shift); report[idx] |= value << bit_shift; value >>= bits_to_set; n -= bits_to_set; bits_to_set = 8; - bit_mask = 0xff; bit_shift = 0; idx++; } /* last nibble */ if (n) { - if (size % 8) - bit_mask &= (1U << (size % 8)) - 1; - report[idx] &= ~bit_mask; - report[idx] |= (value << bit_shift) & bit_mask; + u8 bit_mask = ((1U << n) - 1); + report[idx] &= ~(bit_mask << bit_shift); + report[idx] |= value << bit_shift; } } static void implement(const struct hid_device *hid, u8 *report, unsigned offset, unsigned n, u32 value) { - u64 m; - - if (n > 32) { + if (unlikely(n > 32)) { hid_warn(hid, "%s() called with n (%d) > 32! (%s)\n", __func__, n, current->comm); n = 32; + } else if (n < 32) { + u32 m = (1U << n) - 1; + + if (unlikely(value > m)) { + hid_warn(hid, + "%s() called with too large value %d (n: %d)! (%s)\n", + __func__, value, n, current->comm); + WARN_ON(1); + value &= m; + } } - m = (1ULL << n) - 1; - if (value > m) - hid_warn(hid, "%s() called with too large value %d! (%s)\n", - __func__, value, current->comm); - WARN_ON(value > m); - value &= m; - __implement(report, offset, n, value); } -- cgit v1.1