llama.cpp/common/sampling.h

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#pragma once
#include "llama.h"
#include <string>
#include <vector>
#include <unordered_map>
// sampling parameters
typedef struct llama_sampling_params {
int32_t top_k = 40; // <= 0 to use vocab size
float top_p = 0.95f; // 1.0 = disabled
float tfs_z = 1.00f; // 1.0 = disabled
float typical_p = 1.00f; // 1.0 = disabled
float temp = 0.80f; // 1.0 = disabled
float repeat_penalty = 1.10f; // 1.0 = disabled
int32_t repeat_last_n = 64; // last n tokens to penalize (0 = disable penalty, -1 = context size)
float frequency_penalty = 0.00f; // 0.0 = disabled
float presence_penalty = 0.00f; // 0.0 = disabled
int32_t mirostat = 0; // 0 = disabled, 1 = mirostat, 2 = mirostat 2.0
float mirostat_tau = 5.00f; // target entropy
float mirostat_eta = 0.10f; // learning rate
bool penalize_nl = true; // consider newlines as a repeatable token
int32_t n_probs = 0; // if greater than 0, output the probabilities of top n_probs tokens.
// Classifier-Free Guidance
// https://arxiv.org/abs/2306.17806
std::string cfg_negative_prompt; // string to help guidance
float cfg_scale = 1.f; // How strong is guidance
std::unordered_map<llama_token, float> logit_bias; // logit bias for specific tokens
} llama_sampling_params;
// per-sequence sampler context
typedef struct llama_sampler_sequence_context {
float mirostat_mu; // mirostat sampler state
llama_grammar * grammar;
} llama_sampler_sequence_context;
// general sampler context
typedef struct llama_sampling_context {
~llama_sampling_context();
// parameters that will be used for sampling and when creating
// new llama_sampler_sequence_context instances
llama_sampling_params params;
// map of sequence ids to sampler contexts
std::unordered_map<llama_seq_id, llama_sampler_sequence_context> sequence_contexts;
// when non-NULL, new instances of llama_sampler_sequence_context
// will get a copy of the grammar here
// note: only the pointer is stored here, it is not a copy of
// the grammar and shouldn't be freed
llama_grammar * grammar;
} llama_sampling_context;
#include "common.h"
// Create a new sampling context instance.
llama_sampling_context llama_sampling_context_init(
const struct gpt_params & params,
llama_grammar * grammar = NULL);
// Fetches the sampler context for the specified sequence id (defaults to 0).
// If the context for that sequence id doesn't already exist, it will be created with
// default values based on the parameters in the ctx_sampling argument.
llama_sampler_sequence_context & llama_sampling_get_sequence_context(
llama_sampling_context & ctx_sampling,
const llama_seq_id seq = 0);
// Reset the sampler context for the supplied sequence id (defaults to 0).
// This is necessary to reuse a sequence id or free memory used by sequences
// that are no longer required.
bool llama_sampling_context_reset(
llama_sampling_context & ctx_sampling,
const llama_seq_id seq = 0);
// this is a common sampling function used across the examples for convenience
// it can serve as a starting point for implementing your own sampling function
// Note: When using multiple sequences, it is the caller's responsibility to call
// llama_sampling_context_reset when a sequence ends
//
// required:
// - ctx: context to use for sampling
// - ctx_sampling: sampling-specific context
//
// optional:
// - ctx_guidance: context to use for classifier-free guidance, ignore if NULL
// - last_tokens: needed for repetition penalty, ignore if empty
// - idx: sample from llama_get_logits_ith(ctx, idx)
// - seq: sequence id to associate sampler state with
//
// returns:
// - token: sampled token
// - candidates: vector of candidate tokens
//
llama_token llama_sampling_sample(
struct llama_context * ctx,
struct llama_context * ctx_guidance,
struct llama_sampling_context & ctx_sampling,
const std::vector<llama_token> & last_tokens,
std::vector<llama_token_data> & candidates,
const int idx = 0,
llama_seq_id seq = 0);