llama.cpp/examples/diffusion/diffusion-cli.cpp

#include "arg.h"
#include "chat.h"
#include "common.h"
#include "llama.h"
#include "log.h"

#include <limits.h>

#include <algorithm>
#include <cmath>
#include <cstring>
#include <limits>
#include <random>
#include <string>
#include <vector>

enum diffusion_algorithm { ORIGIN = 0, ENTROPY_BASED = 1, MARGIN_BASED = 2, RANDOM = 3, CONFIDENCE_BASED = 4 };

// Unified transfer scheduling methods
enum transfer_schedule {
    TIMESTEP_BASED = 0,  // Dream-style: (1.0 - s/t) * remaining
    BLOCK_BASED    = 1,  // LLaDA-style: process in blocks with get_num_transfer_tokens
};

typedef bool (*diffusion_step_callback_t)(int32_t             step,
                                          int32_t             total_steps,
                                          const llama_token * tokens,
                                          int32_t             n_tokens,
                                          void *              user_data);

struct diffusion_params {
    int32_t                   steps                   = 0;
    float                     temperature             = 0;
    llama_token               mask_token_id           = LLAMA_TOKEN_NULL;
    diffusion_step_callback_t step_callback           = nullptr;
    void *                    step_callback_user_data = nullptr;
    int32_t                   seed                    = 0;
    bool                      visual_mode             = false;
    bool                      shift_logits            = false;  // Shift logits by -1 after decode

    float   top_p = 0.;
    int32_t top_k = 0.;

    diffusion_algorithm algorithm = CONFIDENCE_BASED;
    transfer_schedule   schedule  = TIMESTEP_BASED;

    float   cfg_scale        = 0.;     // Config scale for classifier-free guidance
    float   eps              = 0.;     // Timestep scheduling
    int32_t block_length     = 0;      // Block size (for block scheduling)
    float   alg_temp         = 0;      // algorithm temperature (0.0 = deterministic)
    bool    add_gumbel_noise = false;  // Add gumbel noise to the logits if temp > 0.0

    int32_t max_length = 0;            // Maximum sequence length
};

struct callback_data {
    diffusion_params *  diff_params;
    const llama_vocab * vocab;
    int32_t             n_input;
};

static float calculate_confidence(const llama_token_data_array & cur_p,
                                  diffusion_algorithm            algorithm,
                                  std::mt19937 &                 rng) {
    switch (algorithm) {
        case CONFIDENCE_BASED:
            return cur_p.data[cur_p.selected].p;  // Selected token probability

        case ENTROPY_BASED:
            {
                float       entropy = 0.0f;
                const float epsilon = 1e-10f;
                for (size_t i = 0; i < cur_p.size; i++) {
                    float prob = cur_p.data[i].p;
                    entropy += prob * logf(prob + epsilon);
                }
                return -entropy;  // Higher entropy = lower confidence
            }

        case MARGIN_BASED:
            return (cur_p.size > 1) ? cur_p.data[0].p - cur_p.data[1].p : cur_p.data[0].p;

        case RANDOM:
            {
                std::uniform_real_distribution<float> uniform(0.0f, 1.0f);
                return uniform(rng);  // Random confidence
            }

        case ORIGIN:
            return cur_p.data[cur_p.selected].p;

        default:
            return 0.0f;
    }
}

// Unified transfer count calculation function
static int32_t calculate_transfer_count(int32_t                      step,
                                        int32_t                      total_steps,
                                        int32_t                      remaining_masked,
                                        transfer_schedule            schedule,
                                        float                        eps,
                                        const std::vector<int32_t> & num_transfer_tokens = {}) {
    switch (schedule) {
        case TIMESTEP_BASED:
            {
                float t          = 1.0f - (float) step / total_steps * (1.0f - eps);
                float s          = 1.0f - (float) (step + 1) / total_steps * (1.0f - eps);
                float p_transfer = (step < total_steps - 1) ? (1.0f - s / t) : 1.0f;
                return (int32_t) (remaining_masked * p_transfer);
            }

        case BLOCK_BASED:
            if (!num_transfer_tokens.empty() && step < (int32_t) num_transfer_tokens.size()) {
                return num_transfer_tokens[step];
            }
            return remaining_masked / (total_steps - step);  // Fallback

        default:
            return remaining_masked / (total_steps - step);
    }
}

static bool diffusion_step_callback(int32_t             step,
                                    int32_t             total_steps,
                                    const llama_token * tokens,
                                    int32_t             n_tokens,
                                    void *              user_data) {
    (void) user_data;

    callback_data * data = static_cast<callback_data *>(user_data);

    auto print_progress_bar = [](int32_t step, int32_t total_steps) {
        int progress_percent = (step * 100) / total_steps;
        int progress_bars    = (step * 50) / total_steps;
        LOG_INF("\rdiffusion step: %d/%d [%s%s] %d%%",
                step,
                total_steps,
                std::string(progress_bars, '=').c_str(),
                std::string(50 - progress_bars, ' ').c_str(),
                progress_percent);
    };

    if (data->diff_params->visual_mode) {
        // Visual mode: clear
        LOG_INF("\033[2J\033[H");  // Clear screen and move cursor to top-left

        print_progress_bar(step, total_steps);

        LOG_INF("\n");

        std::string current_text = " ";

        for (int32_t i = data->n_input; i < n_tokens; i++) {
            std::string token_str;
            if (tokens[i] != llama_vocab_mask(data->vocab)) {
                char piece[256];
                int  n_chars = llama_token_to_piece(data->vocab, tokens[i], piece, sizeof(piece), 0, false);
                if (n_chars > 0) {
                    piece[n_chars] = '\0';
                    token_str      = piece;
                }
            } else {
                token_str = " ";
            }

            current_text += token_str;
        }

        LOG_INF("%s\n", current_text.c_str());
    } else {
        print_progress_bar(step, total_steps);
    }

    return true;
}

static void add_gumbel_noise(float * logits, int32_t n_vocab, float temperature, std::mt19937 & rng) {
    if (temperature == 0.0f) {
        return;
    }

    std::uniform_real_distribution<double> uniform(0.0, 1.0);
    for (int32_t i = 0; i < n_vocab; i++) {
        double noise        = uniform(rng);
        // Prevent log(0)
        noise               = std::max(noise, 1e-20);
        double gumbel_noise = std::pow(-std::log(noise), temperature);
        logits[i]           = std::exp(logits[i]) / gumbel_noise;
    }
}

static std::vector<int32_t> get_num_transfer_tokens(int32_t mask_count, int32_t steps) {
    std::vector<int32_t> num_transfer_tokens(steps);

    int32_t base      = mask_count / steps;
    int32_t remainder = mask_count % steps;

    for (int32_t i = 0; i < steps; i++) {
        num_transfer_tokens[i] = base + (i < remainder ? 1 : 0);
    }

    return num_transfer_tokens;
}

static void diffusion_generate(llama_context *          ctx,
                               const llama_token *      input_tokens,
                               llama_token *            output_tokens,
                               int32_t                  n_input,
                               const diffusion_params & params,
                               int32_t &                n_generated) {
    n_generated = 0;
    if (!ctx || !input_tokens || !output_tokens || n_input <= 0 || params.max_length <= n_input) {
        return;
    }

    const llama_model * model = llama_get_model(ctx);

    // Initialize with input and pad with mask tokens
    std::copy(input_tokens, input_tokens + n_input, output_tokens);
    std::fill(output_tokens + n_input, output_tokens + params.max_length, params.mask_token_id);

    std::mt19937 rng(params.seed);

    llama_set_causal_attn(ctx, false);

    int32_t n_vocab = llama_vocab_n_tokens(llama_model_get_vocab(model));

    std::vector<llama_token_data> candidates(n_vocab);
    std::vector<llama_token_data> conf_candidates;
    conf_candidates.reserve(params.max_length);
    std::vector<int32_t> mask_positions;
    mask_positions.reserve(params.max_length);

    // Setup sampler chain
    struct llama_sampler * sampler = llama_sampler_chain_init(llama_sampler_chain_default_params());
    if (params.top_k > 0) {
        llama_sampler_chain_add(sampler, llama_sampler_init_top_k(params.top_k));
    }
    if (params.top_p < 1.0f) {
        llama_sampler_chain_add(sampler, llama_sampler_init_top_p(params.top_p, 1));
    }
    if (params.temperature > 0.0f) {
        llama_sampler_chain_add(sampler, llama_sampler_init_temp(params.temperature));
    }
    llama_sampler_chain_add(sampler, llama_sampler_init_dist(params.seed));

    struct llama_sampler * dist_sampler = llama_sampler_init_dist(params.seed);

    llama_batch batch = llama_batch_init(params.max_length, 0, 1);
    batch.n_tokens    = params.max_length;

    // Pre-allocate buffers for CFG if needed
    int32_t                  logits_size = n_vocab * params.max_length;
    std::vector<float>       cond_logits_buffer;
    std::vector<llama_token> un_x_buffer;
    if (params.cfg_scale > 0.0f) {
        cond_logits_buffer.resize(logits_size);
        un_x_buffer.resize(params.max_length);
    }

    // For block-based processing
    std::vector<int32_t> num_transfer_tokens;
    int32_t              num_blocks      = 1;
    int32_t              steps_per_block = params.steps;

    if (params.schedule == BLOCK_BASED) {
        GGML_ASSERT(params.max_length % params.block_length == 0);
        num_blocks = params.max_length / params.block_length;
        GGML_ASSERT(params.steps % num_blocks == 0);
        steps_per_block = params.steps / num_blocks;
    }

    std::vector<float> confidence(params.max_length);

    int64_t total_sampling_time = 0;
    int64_t total_time          = 0;
    int64_t time_start          = ggml_time_us();

    for (int block_num = 0; block_num < num_blocks; block_num++) {
        int32_t block_start = (params.schedule == BLOCK_BASED) ? n_input + block_num * params.block_length : 0;
        int32_t block_end   = (params.schedule == BLOCK_BASED) ?
                                  std::min(n_input + (block_num + 1) * params.block_length, params.max_length) :
                                  params.max_length;

        // Count masked tokens in current block for block-based processing
        if (params.schedule == BLOCK_BASED) {
            int32_t block_mask_count = 0;
            for (int i = block_start; i < block_end; i++) {
                if (output_tokens[i] == params.mask_token_id) {
                    block_mask_count++;
                }
            }
            num_transfer_tokens = get_num_transfer_tokens(block_mask_count, steps_per_block);
        }

        for (int32_t step = 0; step < steps_per_block; step++) {
            int32_t global_step = block_num * steps_per_block + step;

            if (params.step_callback) {
                if (!params.step_callback(
                        global_step, params.steps, output_tokens, params.max_length, params.step_callback_user_data)) {
                    break;
                }
            }

            // Setup batch
            for (int32_t i = 0; i < params.max_length; i++) {
                batch.token[i]     = output_tokens[i];
                batch.pos[i]       = i;
                batch.n_seq_id[i]  = 1;
                batch.seq_id[i][0] = 0;
                batch.logits[i]    = 1;
            }

            float * logits = nullptr;

            if (params.cfg_scale > 0.0f) {
                int ret = llama_decode(ctx, batch);
                if (ret != 0) {
                    LOG_ERR("Failed to generate conditional");
                    break;
                }
                float * cond_logits_ptr = llama_get_logits(ctx);
                std::memcpy(cond_logits_buffer.data(), cond_logits_ptr, logits_size * sizeof(float));

                // Unconditional generation (mask input)
                std::copy(output_tokens, output_tokens + params.max_length, un_x_buffer.begin());
                for (int32_t i = 0; i < n_input; i++) {
                    un_x_buffer[i] = params.mask_token_id;
                }

                for (int32_t i = 0; i < params.max_length; i++) {
                    batch.token[i] = un_x_buffer[i];
                }
                ret = llama_decode(ctx, batch);
                if (ret != 0) {
                    LOG_ERR("Failed to generate unconditional");
                    break;
                }
                float * uncond_logits = llama_get_logits(ctx);

                // Apply CFG
                for (int32_t i = 0; i < logits_size; i++) {
                    cond_logits_buffer[i] =
                        uncond_logits[i] + (params.cfg_scale + 1.0f) * (cond_logits_buffer[i] - uncond_logits[i]);
                }
                logits = cond_logits_buffer.data();
            } else {
                int ret = llama_decode(ctx, batch);
                if (ret != 0) {
                    LOG_ERR("%s: failed to decode at step %d, ret = %d\n", __func__, global_step, ret);
                    break;
                }
                logits = llama_get_logits(ctx);
            }

            if (!logits) {
                LOG_ERR("%s: failed to get logits at step %d\n", __func__, global_step);
                break;
            }

            auto get_logits_for_pos = [&](int32_t pos) -> const float * {
                if (params.shift_logits) {
                    return pos == 0 ? logits : logits + (pos - 1) * n_vocab;
                }
                return logits + (pos) *n_vocab;
            };

            int64_t time_start_sampling = ggml_time_us();

            mask_positions.clear();
            for (int32_t i = 0; i < params.max_length; i++) {
                if (output_tokens[i] == params.mask_token_id) {
                    // For block-based, only consider current block
                    if (params.schedule != BLOCK_BASED || (i >= block_start && i < block_end)) {
                        mask_positions.push_back(i);
                    }
                }
            }

            if (mask_positions.empty()) {
                break;
            }

            if (params.add_gumbel_noise && params.temperature > 0.0f) {
                add_gumbel_noise(logits, n_vocab, params.temperature, rng);
            }

            if (params.algorithm == ORIGIN) {
                int32_t transfer_count = calculate_transfer_count(
                    step, steps_per_block, mask_positions.size(), params.schedule, params.eps, num_transfer_tokens);
                float p_transfer = (float) transfer_count / mask_positions.size();

                for (int32_t pos : mask_positions) {
                    if (std::uniform_real_distribution<float>(0.0f, 1.0f)(rng) < p_transfer) {
                        const float * pos_logits = get_logits_for_pos(pos);
                        for (int32_t token_id = 0; token_id < n_vocab; token_id++) {
                            candidates[token_id].id    = token_id;
                            candidates[token_id].logit = pos_logits[token_id];
                            candidates[token_id].p     = 0.0f;
                        }

                        llama_token_data_array cur_p = {
                            candidates.data(),
                            (size_t) n_vocab,
                            -1,
                            false,
                        };

                        llama_sampler_apply(sampler, &cur_p);
                        output_tokens[pos] = cur_p.data[cur_p.selected].id;
                    }
                }
            } else {
                std::vector<std::pair<float, int32_t>> confidences;
                std::vector<llama_token>               sampled_tokens(mask_positions.size());

                for (size_t i = 0; i < mask_positions.size(); i++) {
                    int32_t       pos        = mask_positions[i];
                    const float * pos_logits = get_logits_for_pos(pos);

                    for (int32_t token_id = 0; token_id < n_vocab; token_id++) {
                        candidates[token_id].logit = pos_logits[token_id];
                        candidates[token_id].p     = 0.0f;
                        candidates[token_id].id    = token_id;
                    }

                    llama_token_data_array cur_p = {
                        candidates.data(),
                        candidates.size(),
                        -1,
                        false,
                    };

                    llama_sampler_apply(sampler, &cur_p);
                    llama_token sampled_token = cur_p.data[cur_p.selected].id;

                    float conf = calculate_confidence(cur_p, params.algorithm, rng);

                    sampled_tokens[i] = sampled_token;
                    confidences.emplace_back(conf, i);
                }

                int32_t transfer_count = calculate_transfer_count(
                    step, steps_per_block, mask_positions.size(), params.schedule, params.eps, num_transfer_tokens);

                if (transfer_count > 0) {
                    if (params.alg_temp == 0.0f) {
                        std::partial_sort(confidences.begin(),
                                          confidences.begin() + std::min(transfer_count, (int32_t) confidences.size()),
                                          confidences.end(),
                                          [](const std::pair<float, int32_t> & a, const std::pair<float, int32_t> & b) {
                                              if (a.first != b.first) {
                                                  return a.first > b.first;
                                              }
                                              return a.second < b.second;
                                          });

                        for (int32_t i = 0; i < std::min(transfer_count, (int32_t) confidences.size()); i++) {
                            int32_t mask_idx   = confidences[i].second;
                            int32_t pos        = mask_positions[mask_idx];
                            output_tokens[pos] = sampled_tokens[mask_idx];
                        }
                    } else {
                        conf_candidates.clear();
                        for (size_t i = 0; i < confidences.size(); i++) {
                            float conf_logit = confidences[i].first / params.alg_temp;
                            conf_candidates.emplace_back(llama_token_data{ (int32_t) i, conf_logit, 0.0f });
                        }

                        llama_token_data_array conf_array = {
                            conf_candidates.data(),
                            conf_candidates.size(),
                            -1,
                            false,
                        };

                        for (int32_t i = 0; i < std::min(transfer_count, (int32_t) confidences.size()); i++) {
                            llama_sampler_apply(dist_sampler, &conf_array);
                            int32_t selected_idx = conf_array.selected;
                            int32_t mask_idx     = selected_idx;
                            int32_t pos          = mask_positions[mask_idx];
                            output_tokens[pos]   = sampled_tokens[mask_idx];

                            conf_candidates[selected_idx].p = 0.0f;
                            conf_array.selected             = -1;
                        }
                    }
                }
            }

            int64_t time_end_sampling = ggml_time_us();
            total_sampling_time += time_end_sampling - time_start_sampling;
        }
    }

    int64_t time_end = ggml_time_us();
    total_time += time_end - time_start;

    LOG_INF("\ntotal time: %0.2fms, time per step: %0.2fms, sampling time per step: %0.2fms\n",
            total_time / 1000.0,
            total_time / 1000.0 / params.steps,
            total_sampling_time / 1000.0 / params.steps);

    llama_batch_free(batch);
    llama_sampler_free(sampler);
    llama_sampler_free(dist_sampler);

    n_generated = params.max_length;
}

static std::string format_input_text(const std::string & prompt, const std::string & system_prompt, bool use_chat_template, llama_model * model) {
    if (!use_chat_template) {
        return prompt;
    }

    auto chat_templates = common_chat_templates_init(model, "");
    common_chat_templates_inputs inputs;
    common_chat_msg system_msg;

    if (!system_prompt.empty()) {
        system_msg.role = "system";
        system_msg.content = system_prompt;
        inputs.messages.push_back(system_msg);
    }

    common_chat_msg user_msg;
    user_msg.role = "user";
    user_msg.content = prompt;

    inputs.messages.push_back(user_msg);
    inputs.add_generation_prompt = true;

    auto result = common_chat_templates_apply(chat_templates.get(), inputs);

    return result.prompt;
}

int main(int argc, char ** argv) {
    ggml_time_init();

    common_params params;

    if (!common_params_parse(argc, argv, params, LLAMA_EXAMPLE_DIFFUSION)) {
        return 1;
    }

    common_init();
    llama_backend_init();

    llama_model_params model_params = llama_model_default_params();
    model_params.n_gpu_layers       = params.n_gpu_layers;
    model_params.devices            = params.devices.data();
    model_params.use_mmap           = params.use_mmap;
    model_params.use_mlock          = params.use_mlock;
    model_params.check_tensors      = params.check_tensors;

    llama_model * model = llama_model_load_from_file(params.model.path.c_str(), model_params);
    if (!model) {
        LOG_ERR("error: failed to load model '%s'\n", params.model.path.c_str());
        return 1;
    }

    if (!llama_model_is_diffusion(model)) {
        LOG_ERR("error: unsupported model for diffusion");
        llama_model_free(model);
        return 1;
    }

    llama_context_params ctx_params = llama_context_default_params();
    ctx_params.n_ctx                = params.n_ctx;
    ctx_params.n_batch              = params.n_batch;
    ctx_params.n_ubatch             = params.n_ubatch;
    ctx_params.flash_attn_type      = params.flash_attn_type;
    ctx_params.no_perf              = params.no_perf;
    ctx_params.type_k               = params.cache_type_k;
    ctx_params.type_v               = params.cache_type_v;

    llama_context * ctx = llama_init_from_model(model, ctx_params);
    if (!ctx) {
        LOG_ERR("error: failed to create context\n");
        llama_model_free(model);
        return 1;
    }

    llama_set_n_threads(ctx, params.cpuparams.n_threads, params.cpuparams_batch.n_threads);

    const llama_vocab * vocab            = llama_model_get_vocab(model);

    std::string         formatted_prompt = format_input_text(params.prompt, params.system_prompt, params.enable_chat_template, model);

    std::vector<llama_token> input_tokens = common_tokenize(vocab,
                                                            formatted_prompt,
                                                            /*add special tokens*/ true,
                                                            /*parse special*/ true);

    int n_input = input_tokens.size();

    if (n_input >= params.n_ctx) {
        LOG_ERR("error: input too long (%d tokens), max context is %d\n", n_input, params.n_ctx);
        llama_free(ctx);
        llama_model_free(model);
        return 1;
    }

    llama_token mask_token_id = llama_vocab_mask(vocab);

    GGML_ASSERT(mask_token_id != LLAMA_TOKEN_NULL);

    bool visual_mode = params.diffusion.visual_mode;

    int32_t                  n_generated = 0;
    std::vector<llama_token> output_tokens(params.n_ubatch);

    struct diffusion_params diff_params;

    char shift_logits_str[8];
    if (llama_model_meta_val_str(model, "diffusion.shift_logits", shift_logits_str, sizeof(shift_logits_str)) >= 0) {
        diff_params.shift_logits = (strcmp(shift_logits_str, "true") == 0);
    } else {
        diff_params.shift_logits = true;
    }

    //Use either eps or block length, but not both
    GGML_ASSERT((params.diffusion.eps == 0) ^ (params.diffusion.block_length == 0));

    if (params.diffusion.eps) {
        diff_params.schedule = TIMESTEP_BASED;
        diff_params.eps      = params.diffusion.eps;
    } else if (params.diffusion.block_length) {
        diff_params.schedule     = BLOCK_BASED;
        diff_params.block_length = params.diffusion.block_length;
    }

    diff_params.mask_token_id    = mask_token_id;
    diff_params.seed             = params.sampling.seed;
    diff_params.temperature      = params.sampling.temp;
    diff_params.steps            = params.diffusion.steps;
    diff_params.algorithm        = static_cast<diffusion_algorithm>(params.diffusion.algorithm);
    diff_params.max_length       = params.n_ubatch;
    diff_params.top_p            = params.sampling.top_p;
    diff_params.top_k            = params.sampling.top_k;
    diff_params.visual_mode      = params.diffusion.visual_mode;
    diff_params.add_gumbel_noise = params.diffusion.add_gumbel_noise;

    diff_params.step_callback           = diffusion_step_callback;
    callback_data cb_data               = { &diff_params, vocab, n_input };
    diff_params.step_callback_user_data = &cb_data;

    const char * alg_names[]   = { "ORIGIN", "ENTROPY_BASED", "MARGIN_BASED", "RANDOM", "CONFIDENCE_BASED" };
    const char * sched_names[] = { "TIMESTEP_BASED", "BLOCK_BASED" };
    const char * alg_name =
        (diff_params.algorithm >= 0 && diff_params.algorithm <= 4) ? alg_names[diff_params.algorithm] : "UNKNOWN";
    const char * sched_name =
        (diff_params.schedule >= 0 && diff_params.schedule <= 1) ? sched_names[diff_params.schedule] : "UNKNOWN";

    LOG_INF("diffusion_params: - %-25s llama_token      = %d\n", "mask_token_id", mask_token_id);
    LOG_INF("diffusion_params: - %-25s u32              = %d\n", "steps", diff_params.steps);
    LOG_INF("diffusion_params: - %-25s u32              = %d\n", "max_length", diff_params.max_length);
    LOG_INF("diffusion_params: - %-25s enum             = %d (%s)\n", "algorithm", diff_params.algorithm, alg_name);
    LOG_INF("diffusion_params: - %-25s enum             = %d (%s)\n", "schedule", diff_params.schedule, sched_name);
    LOG_INF("diffusion_params: - %-25s f32              = %.3f\n", "temperature", diff_params.temperature);
    if (diff_params.schedule == TIMESTEP_BASED) {
        LOG_INF("diffusion_params: - %-25s f32              = %.6f\n", "eps", diff_params.eps);
        LOG_INF("diffusion_params: - %-25s f32              = %.3f\n", "alg_temp", diff_params.alg_temp);
    }
    if (diff_params.schedule == BLOCK_BASED) {
        LOG_INF("diffusion_params: - %-25s u32              = %d\n", "block_length", diff_params.block_length);
        LOG_INF("diffusion_params: - %-25s f32              = %.3f\n", "cfg_scale", diff_params.cfg_scale);
    }

    diffusion_generate(ctx, input_tokens.data(), output_tokens.data(), n_input, diff_params, n_generated);

    if (n_generated > 0) {
        if (visual_mode) {
            //clear screen and move cursor to top-left
            LOG_INF("\033[2J\033[H");
        }

        output_tokens.erase(output_tokens.begin(), output_tokens.begin() + n_input);
        std::string output_data = common_detokenize(vocab, output_tokens, false);
        LOG_INF("\n%s\n", output_data.c_str());
    } else {
        LOG_INF("Error: diffusion generation failed\n");
    }

    llama_free(ctx);
    llama_model_free(model);
    llama_backend_free();

    return 0;
}