/************************************************************************
* HELPERS *
************************************************************************/
void *sieve_range(void *arg)
{
bool (*flip_fun)(const int, struct SquareTerms *);
struct IntNode *cand;
struct SieveArg *params = (struct SieveArg *) arg;
struct IntNode **prv = ¶ms->head;
const int until = params->until;
/*
* case where x will be largest corresponds to the third flipping
* quadratic:
*
* 3x² - y² = n where x > y
*
* when y = one less than x = (x - 1)
*
* substituting:
*
* 3x² - (x - 1)² = n
* 2x² + 2x - (1 + n) = 0
*
* from quadratic equation:
* x_max = (-1 + sqrt(3 + 2n)) / 2
*
* add one to ensure that range of x includes x_max:
*/
const int LENGTH_TERMS =
((((int) sqrtf((float) ((until * 2) + 3))) - 1) / 2) + 1;
int x_sq_3[LENGTH_TERMS];
int x_sq_4[LENGTH_TERMS];
for (int x = 2, x_sq; x < LENGTH_TERMS; ++x) {
x_sq = x * x;
x_sq_3[x] = 3 * x_sq;
x_sq_4[x] = 4 * x_sq;
}
struct SquareTerms SQ_TERMS = {
.X_SQ_3 = x_sq_3,
.X_SQ_4 = x_sq_4
};
for (int n = params->start; n < until; n+=2) {
flip_fun = FLIP_MAP[n % 60];
if (flip_fun && flip_fun(n, &SQ_TERMS)) {
cand = handle_malloc(sizeof(struct IntNode));
cand->val = n;
*prv = cand;
prv = &cand->nxt;
}
}
params->last = cand;
pthread_exit(NULL);
}
void JNIFUNCF(ImageFilterGeometry, nativeApplyFilterFlip, jobject src, jint srcWidth, jint srcHeight, jobject dst, jint dstWidth, jint dstHeight, jint flip) {
char* destination = 0;
char* source = 0;
if (srcWidth != dstWidth || srcHeight != dstHeight) {
return;
}
AndroidBitmap_lockPixels(env, src, (void**) &source);
AndroidBitmap_lockPixels(env, dst, (void**) &destination);
flip_fun(flip, source, srcWidth, srcHeight, destination, dstWidth, dstHeight);
AndroidBitmap_unlockPixels(env, dst);
AndroidBitmap_unlockPixels(env, src);
}
static __inline__ void rotate270(char * source, int srcWidth, int srcHeight, char * destination, int dstWidth, int dstHeight){
rotate90(source, srcWidth, srcHeight, destination, dstWidth, dstHeight);
flip_fun(3, destination, dstWidth, dstHeight, destination, dstWidth, dstHeight);
}
__inline__ void rotate180(char * source, int srcWidth, int srcHeight, char * destination, int dstWidth, int dstHeight){
flip_fun(3, source, srcWidth, srcHeight, destination, dstWidth, dstHeight);
}
