Pointers in __crush_do_rule__ function of CRUSH mapper file

[Bobby <italienisch1987@xxxxxxxxx>]

Hi all,

I have a question regarding pointer variables used in the __crush_do_rule__ function of CRUSH __mapper.c__. Can someone please help me understand the purpose of following four pointer variables inside __crush_do_rule__:

int *b = a + result_max;
int *c = b + result_max;
int *w = a;
int *o = b;  

The function __crush_do_rule__ is below:

/**
 * crush_do_rule - calculate a mapping with the given input and rule
 * @map: the crush_map
 * @ruleno: the rule id
 * @x: hash input
 * @result: pointer to result vector
 * @result_max: maximum result size
 * @weight: weight vector (for map leaves)
 * @weight_max: size of weight vector
 * @cwin: Pointer to at least map->working_size bytes of memory or NULL.
 */
int crush_do_rule(const struct crush_map *map,
 int ruleno, int x, int *result, int result_max,
 const __u32 *weight, int weight_max,
 void *cwin, const struct crush_choose_arg *choose_args)
{
int result_len;
struct crush_work *cw = cwin;
int *a = (int *)((char *)cw + map->working_size);
int *b = a + result_max;
int *c = b + result_max;
int *w = a;
int *o = b;
int recurse_to_leaf;
int wsize = 0;
int osize;
int *tmp;
const struct crush_rule *rule;
__u32 step;
int i, j;
int numrep;
int out_size;

Thanks 

Bobby !

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