DSPF_sp_fftSPxSP producing wrong results

I started with the FFT example provided with DSPLIB (version 3.4.0.0) which I found in C:\ti\dsplib_c66x_3_4_0_0\examples\fft_sp_ex\fft_example_sp.c.

I noticed that for many strictly real inputs I tried, the data does not show the expected symmetry. I modified the example and produced the output given below. The DFT function I wrote does not agree with TI's FFT function, but the DFT function does agree with Octave.

Am I missing something here?

I should mention that I've tried this with N = 256, and I get similar results.

Here is my code and my output:

#include <stdint.h>
#include <math.h>
#include <ti/dsplib/dsplib.h>
#include <stdio.h>
#include <complex.h>


#define MAXN 256

#pragma DATA_ALIGN(x_sp, 8);
float   x_sp [2*MAXN];
#pragma DATA_ALIGN(y_sp, 8);
float   y_sp [2*MAXN];
#pragma DATA_ALIGN(w_sp, 8);
float   w_sp [2*MAXN];

unsigned char brev[64] = {
    0x0, 0x20, 0x10, 0x30, 0x8, 0x28, 0x18, 0x38,
    0x4, 0x24, 0x14, 0x34, 0xc, 0x2c, 0x1c, 0x3c,
    0x2, 0x22, 0x12, 0x32, 0xa, 0x2a, 0x1a, 0x3a,
    0x6, 0x26, 0x16, 0x36, 0xe, 0x2e, 0x1e, 0x3e,
    0x1, 0x21, 0x11, 0x31, 0x9, 0x29, 0x19, 0x39,
    0x5, 0x25, 0x15, 0x35, 0xd, 0x2d, 0x1d, 0x3d,
    0x3, 0x23, 0x13, 0x33, 0xb, 0x2b, 0x1b, 0x3b,
    0x7, 0x27, 0x17, 0x37, 0xf, 0x2f, 0x1f, 0x3f
};

static void print_cpx(const float* x, int n)
{
	for(int i = 0; i < n; i++)
		printf("%4d: %10.4f %+10.4fi\n",i, x[2*i],x[2*i+1] );
	printf("\n");
}

void generateInput(int N) {
    for(int i = 0; i < N; ++i) {
    	x_sp[2*i]  = (float)i/4.0f;
    	x_sp[2*i] += (i%4)==0 ? 1.0f : 0.0f;
    	x_sp[2*i+1] = 0.0f;
    }
}

// a simple (but slow N^2) DFT function.
void slow_dft( const float complex* xin, float complex* xout, unsigned int N )
{
	double twoPi_N = 2.0f*3.141592654/(double)N;

    for(int k = 0; k < N; ++k)
    {
        double complex Xk = 0.0;

        double w = k*twoPi_N;

        for(int n = 0; n < N; ++n)
        {
        	double complex e_iwn = cexp(-I*w*n);
            Xk += xin[n]*e_iwn;
        }

        xout[k] = (float complex)Xk;
    }
}


/* Function for generating Specialized sequence of twiddle factors */
void gen_twiddle_fft_sp (float *w, int n)
{
    int i, j, k;
    double x_t, y_t, theta1, theta2, theta3;
    const double PI = 3.141592654;

    for (j = 1, k = 0; j <= n >> 2; j = j << 2)
    {
        for (i = 0; i < n >> 2; i += j)
        {
            theta1 = 2 * PI * i / n;
            x_t = cos (theta1);
            y_t = sin (theta1);
            w[k] = (float) x_t;
            w[k + 1] = (float) y_t;

            theta2 = 4 * PI * i / n;
            x_t = cos (theta2);
            y_t = sin (theta2);
            w[k + 2] = (float) x_t;
            w[k + 3] = (float) y_t;

            theta3 = 6 * PI * i / n;
            x_t = cos (theta3);
            y_t = sin (theta3);
            w[k + 4] = (float) x_t;
            w[k + 5] = (float) y_t;
            k += 6;
        }
    }
}


void main (void) {

       int N = 16;

	/* Generate the input data */
	generateInput(N);
	printf("Input:\n");
	print_cpx(x_sp,N);

	/* Genarate twiddle factors */
	gen_twiddle_fft_sp(w_sp, N);

	/* Call FFT routine */
	DSPF_sp_fftSPxSP(N, x_sp, w_sp, y_sp, brev, 4, 0, N);
	printf("TI FFT:\n");
    print_cpx(y_sp,N);


    /* Re-generate the input data */
    generateInput(N);
    slow_dft((const float complex*)x_sp,(float complex*)y_sp,N);
    printf("Simple DFT:\n");
    print_cpx(y_sp,N);
}

///////////////////////////////////////////////////////////////////////////

Input:
   0:     1.0000    +0.0000i
   1:     0.2500    +0.0000i
   2:     0.5000    +0.0000i
   3:     0.7500    +0.0000i
   4:     2.0000    +0.0000i
   5:     1.2500    +0.0000i
   6:     1.5000    +0.0000i
   7:     1.7500    +0.0000i
   8:     3.0000    +0.0000i
   9:     2.2500    +0.0000i
  10:     2.5000    +0.0000i
  11:     2.7500    +0.0000i
  12:     4.0000    +0.0000i
  13:     3.2500    +0.0000i
  14:     3.5000    +0.0000i
  15:     3.7500    +0.0000i

TI FFT:
   0:    34.0000    +0.0000i
   1:     2.0000   +10.0547i
   2:    -4.8284    +2.0000i
   3:    -2.0000    -2.9932i
   4:     2.0000    +2.0000i
   5:     2.0000    -2.9932i
   6:     4.8284    +2.0000i
   7:    -2.0000   +10.0547i
   8:     2.0000    +0.0000i
   9:     2.0000    -0.3978i
  10:     0.8284    +2.0000i
  11:    -2.0000    +1.3364i
  12:     2.0000    -2.0000i
  13:     2.0000    +1.3364i
  14:    -0.8284    +2.0000i
  15:    -2.0000    -0.3978i

Simple DFT:
   0:    34.0000    +0.0000i
   1:    -2.0000   +10.0547i
   2:    -2.0000    +4.8284i
   3:    -2.0000    +2.9932i
   4:     2.0000    +2.0000i
   5:    -2.0000    +1.3364i
   6:    -2.0000    +0.8284i
   7:    -2.0000    +0.3978i
   8:     2.0000    +0.0000i
   9:    -2.0000    -0.3978i
  10:    -2.0000    -0.8284i
  11:    -2.0000    -1.3364i
  12:     2.0000    -2.0000i
  13:    -2.0000    -2.9932i
  14:    -2.0000    -4.8284i
  15:    -2.0000   -10.0547i