Switch to u64 arithmetic and use DIV_ROUND_CLOSEST_ULL() to avoid
the overflow.
buffer[i] is unsigned int and is limited by the lirc core to
IR_MAX_DURATION, which is 500000.
idata->freq is u32, which has a max value of 0xFFFFFFFF.
In the case where buffer[i] is 500000, idata->freq overflows the u32
multiplication for any values >= 8590.
0xFFFFFFFF / 500000 ~= 8589
By casting buffer[i] to u64, idata->freq can be any u32 value without
overflowing the multiplication.
0xFFFFFFFFFFFFFFFF / 500000 ~=
36893488147419 (>
4294967295)
The result of the final operation will fit back into the unsigned int
limits without any issues.
500000 * 0xFFFFFFFF /
1000000 = 0x80000000 (< 0xFFFFFFFF)
Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
/* convert the pulse/space signal to raw binary signal */
for (i = 0; i < count; i++) {
- buffer[i] = DIV_ROUND_CLOSEST(buffer[i] * idata->freq, 1000000);
+ buffer[i] = DIV_ROUND_CLOSEST_ULL((u64)buffer[i] * idata->freq,
+ 1000000);
len += buffer[i];
}