/* forward transform, sign = -1; transform length = 3 * 2^n */
int
four_step_fnt(mpd_uint_t *a, mpd_size_t n, int modnum)
{
mpd_size_t R = 3; /* number of rows */
mpd_size_t C = n / 3; /* number of columns */
mpd_uint_t w3table[3];
mpd_uint_t kernel, w0, w1, wstep;
mpd_uint_t *s, *p0, *p1, *p2;
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_size_t i, k;
assert(n >= 48);
assert(n <= 3*MPD_MAXTRANSFORM_2N);
SETMODULUS(modnum);
_mpd_init_w3table(w3table, -1, modnum);
/* size three ntt on the columns */
for (p0=a, p1=p0+C, p2=p0+2*C; p0<a+C; p0++,p1++,p2++) {
SIZE3_NTT(p0, p1, p2, w3table);
}
kernel = _mpd_getkernel(n, -1, modnum);
for (i = 1; i < R; i++) {
w0 = 1;
w1 = POWMOD(kernel, i);
wstep = MULMOD(w1, w1);
for (k = 0; k < C-1; k += 2) {
mpd_uint_t x0 = a[i*C+k];
mpd_uint_t x1 = a[i*C+k+1];
MULMOD2(&x0, w0, &x1, w1);
MULMOD2C(&w0, &w1, wstep);
a[i*C+k] = x0;
a[i*C+k+1] = x1;
}
}
/* transform rows */
for (s = a; s < a+n; s += C) {
if (!six_step_fnt(s, C, modnum)) {
return 0;
}
}
#if 0
/* An unordered transform is sufficient for convolution. */
if (ordered) {
transpose_3xpow2(a, R, C);
}
#endif
return 1;
}
/* backward transform, sign = 1; transform length = 3 * 2**n */
int
inv_four_step_fnt(const mpd_context_t *ctx, mpd_uint_t *a, mpd_size_t n, int modnum)
{
mpd_size_t R = 3; /* number of rows */
mpd_size_t C = n / 3; /* number of columns */
mpd_uint_t w3table[3];
mpd_uint_t kernel, w0, w1, wstep;
mpd_uint_t *s, *p0, *p1, *p2;
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_size_t i, k;
assert(n >= 48);
assert(n <= 3*MPD_MAXTRANSFORM_2N);
#if 0
/* An unordered transform is sufficient for convolution. */
/* Transpose the matrix, producing an R*C matrix. */
transpose_3xpow2(a, C, R);
#endif
/* Length C transform on the rows. */
for (s = a; s < a+n; s += C) {
if (!inv_six_step_fnt(ctx, s, C, modnum)) {
return 0;
}
}
/* Multiply each matrix element (addressed by i*C+k) by r**(i*k). */
SETMODULUS(modnum);
kernel = _mpd_getkernel(n, 1, modnum);
for (i = 1; i < R; i++) {
w0 = 1;
w1 = POWMOD(kernel, i);
wstep = MULMOD(w1, w1);
for (k = 0; k < C; k += 2) {
mpd_uint_t x0 = a[i*C+k];
mpd_uint_t x1 = a[i*C+k+1];
MULMOD2(&x0, w0, &x1, w1);
MULMOD2C(&w0, &w1, wstep);
a[i*C+k] = x0;
a[i*C+k+1] = x1;
}
}
/* Length R transform on the columns. */
_mpd_init_w3table(w3table, 1, modnum);
for (p0=a, p1=p0+C, p2=p0+2*C; p0<a+C; p0++,p1++,p2++) {
SIZE3_NTT(p0, p1, p2, w3table);
}
return 1;
}
/* initialize transform parameters */
struct fnt_params *
_mpd_init_fnt_params(mpd_size_t n, int sign, int modnum)
{
struct fnt_params *tparams;
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_uint_t kernel, imag, w;
mpd_uint_t i;
mpd_size_t nhalf;
assert(ispower2(n));
assert(sign == -1 || sign == 1);
assert(P1 <= modnum && modnum <= P3);
nhalf = n/2;
tparams = mpd_sh_alloc(sizeof *tparams, nhalf, sizeof (mpd_uint_t));
if (tparams == NULL) {
return NULL;
}
SETMODULUS(modnum);
kernel = _mpd_getkernel(n, sign, modnum);
imag = _mpd_getkernel(4, -sign, modnum);
tparams->modnum = modnum;
tparams->modulus = umod;
tparams->imag = imag;
tparams->kernel = kernel;
w = 1;
for (i = 0; i < nhalf; i++) {
tparams->wtable[i] = w;
w = MULMOD(w, kernel);
}
return tparams;
}
/* initialize wtable of size three */
void
_mpd_init_w3table(mpd_uint_t w3table[3], int sign, int modnum)
{
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_uint_t kernel;
SETMODULUS(modnum);
kernel = _mpd_getkernel(3, sign, modnum);
w3table[0] = 1;
w3table[1] = kernel;
w3table[2] = POWMOD(kernel, 2);
}
/* forward transform with sign = -1 */
int
six_step_fnt(mpd_uint_t *a, mpd_size_t n, int modnum)
{
struct fnt_params *tparams;
mpd_size_t log2n, C, R;
mpd_uint_t kernel;
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_uint_t *x, w0, w1, wstep;
mpd_size_t i, k;
assert(ispower2(n));
assert(n >= 16);
assert(n <= MPD_MAXTRANSFORM_2N);
log2n = mpd_bsr(n);
C = ((mpd_size_t)1) << (log2n / 2); /* number of columns */
R = ((mpd_size_t)1) << (log2n - (log2n / 2)); /* number of rows */
/* Transpose the matrix. */
if (!transpose_pow2(a, R, C)) {
return 0;
}
/* Length R transform on the rows. */
if ((tparams = _mpd_init_fnt_params(R, -1, modnum)) == NULL) {
return 0;
}
for (x = a; x < a+n; x += R) {
fnt_dif2(x, R, tparams);
}
/* Transpose the matrix. */
if (!transpose_pow2(a, C, R)) {
mpd_free(tparams);
return 0;
}
/* Multiply each matrix element (addressed by i*C+k) by r**(i*k). */
SETMODULUS(modnum);
kernel = _mpd_getkernel(n, -1, modnum);
for (i = 1; i < R; i++) {
w0 = 1; /* r**(i*0): initial value for k=0 */
w1 = POWMOD(kernel, i); /* r**(i*1): initial value for k=1 */
wstep = MULMOD(w1, w1); /* r**(2*i) */
for (k = 0; k < C; k += 2) {
mpd_uint_t x0 = a[i*C+k];
mpd_uint_t x1 = a[i*C+k+1];
MULMOD2(&x0, w0, &x1, w1);
MULMOD2C(&w0, &w1, wstep); /* r**(i*(k+2)) = r**(i*k) * r**(2*i) */
a[i*C+k] = x0;
a[i*C+k+1] = x1;
}
}
/* Length C transform on the rows. */
if (C != R) {
mpd_free(tparams);
if ((tparams = _mpd_init_fnt_params(C, -1, modnum)) == NULL) {
return 0;
}
}
for (x = a; x < a+n; x += C) {
fnt_dif2(x, C, tparams);
}
mpd_free(tparams);
#if 0
/* An unordered transform is sufficient for convolution. */
/* Transpose the matrix. */
if (!transpose_pow2(a, R, C)) {
return 0;
}
#endif
return 1;
}
