Function ggml_im2col

ggml.c:5346–5390

im2col: [N, IC, IH, IW] => [N, OH, OW, IC*KH*KW] a: [OC，IC, KH, KW] b: [N, IC, IH, IW] result: [N, OH, OW, IC*KH*KW]

// b: [N, IC, IH, IW]
// result: [N, OH, OW, IC*KH*KW]
struct ggml_tensor * ggml_im2col(
    struct ggml_context * ctx,
    struct ggml_tensor  * a,
    struct ggml_tensor  * b,
    int                  s0,
    int                  s1,
    int                  p0,
    int                  p1,
    int                  d0,
    int                  d1,
    bool                 is_2D) {

    if(is_2D) {
        GGML_ASSERT(a->ne[2] == b->ne[2]);
    } else {
        GGML_ASSERT(a->ne[1] == b->ne[1]);
    }
    bool is_node = false;

    if (a->grad || b->grad) {
        GGML_ASSERT(false); // TODO: implement backward
        is_node = true;
    }

    const int64_t OH = is_2D ? ggml_calc_conv_output_size(b->ne[1], a->ne[1], s1, p1, d1) : 0;
    const int64_t OW =         ggml_calc_conv_output_size(b->ne[0], a->ne[0], s0, p0, d0);

    const int64_t ne[4] = {
        is_2D ? (a->ne[2] * a->ne[1] * a->ne[0]) : a->ne[1] * a->ne[0],
        OW,
        is_2D ? OH : b->ne[2],
        is_2D ?      b->ne[3] : 1,
    };

    struct ggml_tensor * result = ggml_new_tensor(ctx, GGML_TYPE_F16, 4, ne);
    int32_t params[] = { s0, s1, p0, p1, d0, d1, (is_2D ? 1 : 0) };
    ggml_set_op_params(result, params, sizeof(params));

    result->op = GGML_OP_IM2COL;
    result->grad = is_node ? ggml_dup_tensor(ctx, result) : NULL;
    result->src[0] = a;
    result->src[1] = b;

    return result;
}

// a: [OC，IC, KH, KW]
// b: [N, IC, IH, IW]