[[docs:funcstructs:ggml-impl.h]]
== ggml-impl.h


[[docs:funcstructs:ggml-impl.h:struct-ggml_hash_set]]
=== struct ggml_hash_set

[source,C++]
----
struct ggml_hash_set {
    size_t size;
    ggml_bitset_t * used;       // whether or not the keys are in use i.e. set
    struct ggml_tensor ** keys; // actual tensors in the set, keys[i] is only defined if ggml_bitset_get(used, i)
};
----

Hash table with linear probing. Used with the following functions (note that there are no functions for deleting individual keys):

* [.codebit]#`struct ggml_hash_set ggml_hash_set_new(size_t size)`#: (declared in ggml-impl.h, defined in ggml.c)
* [.codebit]#`void ggml_hash_set_free(struct ggml_hash_set * hash_set)`#: frees allocated memory (declared in ggml-impl.h, defined in ggml.c)
* [.codebit]#`size_t ggml_hash_size(size_t min_sz)`#: "returns the minimum size for a hash set that can hold min_sz elements", i.e. the smallest prime number greater than min_sz (declared in ggml-impl.h, defined in ggml.c)
* [.codebit]#`void ggml_hash_set_reset(struct ggml_hash_set * hash_set)`#: marks all keys as unused (declared in ggml-impl.h, defined in ggml.c)
* [.codebit]#`static bool ggml_hash_contains(const struct ggml_hash_set * hash_set, struct ggml_tensor * key)`#: (declared and defined in ggml-impl.h)
* [.codebit]#`static size_t ggml_hash_find(const struct ggml_hash_set * hash_set, const struct ggml_tensor * key)`#: "returns GGML_HASHSET_FULL if table is full, otherwise the current index of the key or where it should be inserted" (declared and defined in ggml-impl.h)
* [.codebit]#`static size_t ggml_hash_insert(struct ggml_hash_set * hash_set, struct ggml_tensor * key)`#: "returns GGML_HASHSET_ALREADY_EXISTS if key already exists, index otherwise, asserts if table is full" (declared and defined in ggml-impl.h)
* [.codebit]#`static size_t ggml_hash_find_or_insert(struct ggml_hash_set * hash_set, struct ggml_tensor * key)`#: (declared and defined in ggml-impl.h)

[[docs:funcstructs:ggml-impl.h:ggml_hash]]
=== ggml_hash

Signature:
[.codebit]#`static inline size_t ggml_hash(const struct ggml_tensor * p)`#

[source,C++]
----
// the last 4 bits are always zero due to alignment
return (size_t)(uintptr_t)p >> 4;
----


[[docs:funcstructs:ggml-impl.h:enum-ggml_cgraph_eval_order]]
=== enum ggml_cgraph_eval_order

[source,C++]
----
enum ggml_cgraph_eval_order {
    GGML_CGRAPH_EVAL_ORDER_LEFT_TO_RIGHT = 0,
    GGML_CGRAPH_EVAL_ORDER_RIGHT_TO_LEFT,
    GGML_CGRAPH_EVAL_ORDER_COUNT
};
----

Computation graph evaluation order. Default is [.codebit]#`GGML_CGRAPH_EVAL_ORDER_LEFT_TO_RIGHT`# (see [.codebit]#`ggml_new_graph_custom(...)`#).


[[docs:funcstructs:ggml-impl.h:struct-ggml_cgraph]]
=== struct ggml_cgraph

[source,C++]
----
struct ggml_cgraph {
    int size;    // maximum number of nodes/leafs/grads/grad_accs
    int n_nodes; // number of nodes currently in use
    int n_leafs; // number of leafs currently in use

    struct ggml_tensor ** nodes;     // tensors with data that can change if the graph is evaluated
    struct ggml_tensor ** grads;     // the outputs of these tensors are the gradients of the nodes
    struct ggml_tensor ** grad_accs; // accumulators for node gradients
    struct ggml_tensor ** leafs;     // tensors with constant data

    struct ggml_hash_set visited_hash_set;

    enum ggml_cgraph_eval_order order;
};
----