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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2016-04-06 10:19:58 -0700
committerJiri Kosina <jkosina@suse.cz>2016-04-07 15:45:09 +0200
commit95d1c8951e5bd50bb89654a99a7012b1e75646bd (patch)
tree80f1e3f656c80f7ef27c0159418f69cce68ce731 /drivers/hid/hid-core.c
parent6edac6fde59e231bd297ebcbc3d1bd395006cd1d (diff)
downloadlinux-95d1c8951e5bd50bb89654a99a7012b1e75646bd.tar.bz2
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 <dianders@chromium.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid/hid-core.c')
-rw-r--r--drivers/hid/hid-core.c33
1 files changed, 15 insertions, 18 deletions
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index bdb8cc89cacc..9985c0ab7c7f 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);
}