diff options
Diffstat (limited to 'linux/drivers/media/video')
| -rw-r--r-- | linux/drivers/media/video/cx88/cx88-dsp.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/linux/drivers/media/video/cx88/cx88-dsp.c b/linux/drivers/media/video/cx88/cx88-dsp.c index da2b306c0..262bda9ec 100644 --- a/linux/drivers/media/video/cx88/cx88-dsp.c +++ b/linux/drivers/media/video/cx88/cx88-dsp.c @@ -100,13 +100,22 @@ static u32 int_goertzel(s16 x[], u32 N, u32 freq) s32 s_prev2 = 0; s32 coeff = 2*int_cos(freq); u32 i; + + s64 tmp; + u32 remainder; + for (i = 0; i < N; i++) { s32 s = x[i] + ((s64)coeff*s_prev/32768) - s_prev2; s_prev2 = s_prev; s_prev = s; } - return (u32)(((s64)s_prev2*s_prev2 + (s64)s_prev*s_prev - - (s64)coeff*s_prev2*s_prev/32768)/N/N); + + tmp = (s64)s_prev2*s_prev2 + (s64)s_prev*s_prev - + (s64)coeff*s_prev2*s_prev/32768; + + /* XXX: N must be low enough so that N*N fits in s32. + * Else we need two divisions. */ + return (u32) div_s64_rem(tmp, N*N, &remainder); } static u32 freq_magnitude(s16 x[], u32 N, u32 freq) |