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Commit ec44ed07 authored by John Grossman's avatar John Grossman
Browse files

Utils: Fix a bug in the linear transformation code. 



Hand merge from ics-aah

> Utils: Fix a bug in the linear transformation code.
>
> Fix a bug where an incorrect result would be computed if you used the
> linear transformation code to do a reverse transformation (from B's
> domain into A's domain) when the scaler fraction was negative.
>
> Change-Id: I8e5f109314d235a177ab41f65d3c4cd08cff78be
> Signed-off-by: default avatarJohn Grossman <johngro@google.com>

Change-Id: Id90e18f685c61c1a89fd91c32adcf01363b3e8f3
Signed-off-by: default avatarJohn Grossman <johngro@google.com>
parent 3443b333

libs/utils/LinearTransform.cpp

+6 −3
Original line number Diff line number Diff line
@@ -114,6 +114,7 @@ static bool linear_transform_s64_to_s64( 
        int64_t  basis1,

        int32_t  N,

        uint32_t D,

        bool     invert_frac,

        int64_t  basis2,

        int64_t* out) {

    uint64_t scaled, res;
@@ -137,8 +138,8 @@ static bool linear_transform_s64_to_s64( 
        is_neg = !is_neg;



    if (!scale_u64_to_u64(abs_val,

                          ABS(N),

                          D,

                          invert_frac ? D : ABS(N),

                          invert_frac ? ABS(N) : D,

                          &scaled,

                          is_neg))

        return false; // overflow/undeflow
@@ -191,6 +192,7 @@ bool LinearTransform::doForwardTransform(int64_t a_in, int64_t* b_out) const { 
                                       a_zero,

                                       a_to_b_numer,

                                       a_to_b_denom,

                                       false,

                                       b_zero,

                                       b_out);

}
@@ -201,8 +203,9 @@ bool LinearTransform::doReverseTransform(int64_t b_in, int64_t* a_out) const { 


    return linear_transform_s64_to_s64(b_in,

                                       b_zero,

                                       a_to_b_denom,

                                       a_to_b_numer,

                                       a_to_b_denom,

                                       true,

                                       a_zero,

                                       a_out);

}