N-gram hashes
×no parametersself.engram_hash(input_ids, start_pos, engram_mask) · 1252
For each position, hash the 2-, 3- and 4-gram of normalized tokens ending there into 8 row indices each, for each Engram table.
- in
- [B batch, T positions]
- out
- [B batch, T positions, 2 Engram layers, 24 n-grams × heads]
Token IDs are first mapped to 99,092 normalized IDs, so that tokens whose text differs only in case, accents or spacing share one (engram.py 17–61); the vocabulary file needed to rebuild that map is not pinned. An n-gram does not reach across the start of the sequence or an image position.
Codeengram.py 159–184 · 2 more files
@torch.inference_mode()
def forward(self, input_ids: torch.Tensor, start_pos: int, token_mask: torch.Tensor | None = None) -> torch.Tensor:
"""token_mask: [B, L], False for tokens that take no part in an n-gram (image spans).
Returns the hash ids, shaped [B, L, n_engram_layers, n_hash_cols]."""
batch, seqlen = input_ids.shape
compressed = self.token_map[input_ids]
if token_mask is not None:
compressed = torch.where(token_mask, compressed, self.DEAD)
self.cache[:batch, start_pos : start_pos + seqlen] = compressed
positions = torch.arange(start_pos, start_pos + seqlen, device=input_ids.device).expand(batch, seqlen)
tokens, blocked = [], torch.zeros_like(positions, dtype=torch.bool)
for shift in range(self.layout.max_ngram_size):
source = self.cache[:batch].gather(1, (positions - shift).clamp_min(0))
blocked = blocked | (positions < shift) | (source == self.DEAD)
tokens.append(torch.where(blocked, self.pad_id, source))
tokens = torch.stack(tokens, dim=-1) # [B, L, max_ngram_size]
# XOR the multiplied ids together one lookback at a time, so the running value after step i
# is the hash of the (i+1)-gram; each lands in its own prime-sized bucket range
products = tokens.unsqueeze(2) * self.multipliers # [B, L, n_engram_layers, max_ngram_size]
rolling, hashes = products[..., 0], []
for i in range(1, self.layout.max_ngram_size):
rolling = torch.bitwise_xor(rolling, products[..., i])
hashes.append(rolling.unsqueeze(-1) % self.primes[:, i - 1])
return torch.cat(hashes, dim=-1) + self.offsets @torch.inference_mode()
def forward(
self, input_ids: torch.Tensor, start_pos: int = 0, images=None, token_types: torch.Tensor | None = None
):
"""input_ids: [b, s], every entry a real token id -- generate.py only ever passes positions it
has already filled, so the padding it uses internally never reaches here. token_types /
images carry the VL inputs built by image_processor.prepare_vl_inputs; image spans must lie
inside the first (start_pos 0) chunk."""
image_mask = None if token_types is None else token_types >= 0 # TEXT is -1
# image tokens take no part in an n-gram and get no engram contribution; text-only needs no mask
engram_mask = None if image_mask is None else ~image_mask
engram_hashes = self.engram_hash(input_ids, start_pos, engram_mask) if self.engram_hash is not None else None
h = self.embed(input_ids)
if images is not None:
assert start_pos == 0, "image spans must be prefilled in a single chunk"
self.merge_image_embeddings(images, h)
# Expand to hc_mult copies for Hyper-Connections
h = h.unsqueeze(2).repeat(1, 1, self.hc_mult, 1)
main_hiddens = []
pre_mix = make_identity_pre_mix(h, self.hc_mult)
for i, layer in enumerate(self.layers):
if layer.engram is not None:
h = layer.engram(h, engram_hashes[:, :, layer.engram.layer_hash_index, :], engram_mask)
# the MTP head reads the attention input of its target layers, not their output
if i in self.target_layer_ids:
main_hiddens.append(h.mean(dim=2))
h, pre_mix = layer(h, start_pos, pre_mix, image_mask)
h = layer.hc_pre(h, pre_mix)
logits = self.head(self.norm(h))
output_ids = sample(logits, self.temperature)
main_hidden = torch.cat(main_hiddens, dim=-1) if main_hiddens else None
return output_ids, logits, main_hidden{
"vocab_size": 129280,
"dim": 5120,
"moe_inter_dim": 2304,
"n_layers": 40,
"n_mtp_layers": 3,
"dspark_block_size": 5,
"dspark_noise_token_id": 128799,
"dspark_target_layer_ids": [37, 38, 39],
"dspark_markov_rank": 256,
"dspark_n_routed_experts": 128,
"dspark_n_activated_experts": 3,
"n_heads": 64,
"n_routed_experts": 384,
"n_shared_experts": 1,
"n_activated_experts": 6,
"score_func": "sqrtsoftplus",
"route_scale": 1.5,
"swiglu_limit": 10.0,
"q_lora_rank": 1280,
"head_dim": 512,
"rope_head_dim": 64,
"norm_eps": 1e-20,
"o_groups": 8,
"o_lora_rank": 1024,
"window_size": 128,
"kv_source_layers": [2, 8, 14, 20],
"index_source_layers": [2, 8, 14, 20, 24, 28, 32, 36],
"original_seq_len": 65536,
"rope_theta": 10000,
"rope_factor": 16,
"beta_fast": 32,
"beta_slow": 1,
"index_n_heads": 32,
"index_head_dim": 128,
"index_topk": 512,
"candidate_source_layer": 20,
"candidate_topk_blocks": 2048,
"candidate_block_size": 8,
"hc_mult": 4,
"hc_sinkhorn_iters": 20,
"hc_eps": 1e-06,
"engram_layer_ids": [1, 14],
"engram_vocab_size": 16000000,
"engram_num_embeddings": [384006168, 384016682],
"engram_max_ngram_size": 4,
"engram_pad_id": 2,
"engram_compressed_vocab_size": 99092,
"dtype": "fp8",
"expert_dtype": "fp4",
"compress_rope_theta": 160000,
"compress_ratios": [0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
"vision_n_layers": 32,
"vision_dim": 1024,
"vision_n_heads": 16,
"vision_inter_dim": 2816,
"vision_patch_size": 14,
"vision_downsample_ratio": 3,
"vision_max_n_token": 1024,
"vision_min_pixels": 295936,
"vision_max_wh_ratio": null,
"image_token_id": 129264,
"engram_n_heads": 8,
"engram_head_dim": 256,
"vision_rope_theta": 10000
}Sources3
Direct evidence
Each position hashes its 2-, 3- and 4-gram of normalised token ids, each modulo eight primes, into row indices of each Engram layer’s table; an n-gram does not reach across the start of the sequence or an image position.
engram-hash · deepseek-ai/DeepSeek-V4.1-Flash / inference/engram.py
Pinned revision 2cba9e42aa02 ↗ · lines 159–184
Read code excerpt
@torch.inference_mode()
def forward(self, input_ids: torch.Tensor, start_pos: int, token_mask: torch.Tensor | None = None) -> torch.Tensor:
"""token_mask: [B, L], False for tokens that take no part in an n-gram (image spans).
Returns the hash ids, shaped [B, L, n_engram_layers, n_hash_cols]."""
batch, seqlen = input_ids.shape
compressed = self.token_map[input_ids]
if token_mask is not None:
compressed = torch.where(token_mask, compressed, self.DEAD)
self.cache[:batch, start_pos : start_pos + seqlen] = compressed
positions = torch.arange(start_pos, start_pos + seqlen, device=input_ids.device).expand(batch, seqlen)
tokens, blocked = [], torch.zeros_like(positions, dtype=torch.bool)
for shift in range(self.layout.max_ngram_size):
source = self.cache[:batch].gather(1, (positions - shift).clamp_min(0))
blocked = blocked | (positions < shift) | (source == self.DEAD)
tokens.append(torch.where(blocked, self.pad_id, source))
tokens = torch.stack(tokens, dim=-1) # [B, L, max_ngram_size]
# XOR the multiplied ids together one lookback at a time, so the running value after step i
# is the hash of the (i+1)-gram; each lands in its own prime-sized bucket range
products = tokens.unsqueeze(2) * self.multipliers # [B, L, n_engram_layers, max_ngram_size]
rolling, hashes = products[..., 0], []
for i in range(1, self.layout.max_ngram_size):
rolling = torch.bitwise_xor(rolling, products[..., i])
hashes.append(rolling.unsqueeze(-1) % self.primes[:, i - 1])
return torch.cat(hashes, dim=-1) + self.offsetsDirect evidence
Tokens are embedded and repeated into four streams; each layer, after an Engram step where it has one, reads and writes the streams; the last reading mix collapses them, then the final norm and the head.
transformer-forward · deepseek-ai/DeepSeek-V4.1-Flash / inference/model.py
Pinned revision 2cba9e42aa02 ↗ · lines 1241–1272
Read code excerpt
@torch.inference_mode()
def forward(
self, input_ids: torch.Tensor, start_pos: int = 0, images=None, token_types: torch.Tensor | None = None
):
"""input_ids: [b, s], every entry a real token id -- generate.py only ever passes positions it
has already filled, so the padding it uses internally never reaches here. token_types /
images carry the VL inputs built by image_processor.prepare_vl_inputs; image spans must lie
inside the first (start_pos 0) chunk."""
image_mask = None if token_types is None else token_types >= 0 # TEXT is -1
# image tokens take no part in an n-gram and get no engram contribution; text-only needs no mask
engram_mask = None if image_mask is None else ~image_mask
engram_hashes = self.engram_hash(input_ids, start_pos, engram_mask) if self.engram_hash is not None else None
h = self.embed(input_ids)
if images is not None:
assert start_pos == 0, "image spans must be prefilled in a single chunk"
self.merge_image_embeddings(images, h)
# Expand to hc_mult copies for Hyper-Connections
h = h.unsqueeze(2).repeat(1, 1, self.hc_mult, 1)
main_hiddens = []
pre_mix = make_identity_pre_mix(h, self.hc_mult)
for i, layer in enumerate(self.layers):
if layer.engram is not None:
h = layer.engram(h, engram_hashes[:, :, layer.engram.layer_hash_index, :], engram_mask)
# the MTP head reads the attention input of its target layers, not their output
if i in self.target_layer_ids:
main_hiddens.append(h.mean(dim=2))
h, pre_mix = layer(h, start_pos, pre_mix, image_mask)
h = layer.hc_pre(h, pre_mix)
logits = self.head(self.norm(h))
output_ids = sample(logits, self.temperature)
main_hidden = torch.cat(main_hiddens, dim=-1) if main_hiddens else None
return output_ids, logits, main_hiddenDirect evidence
The reference configuration: 40 layers of width 5,120, 64 heads of 512 features with a 64-feature rotary part, a 1,280-feature query latent, a grouped output of 8 groups at rank 1,024, a window of 128, the per-layer compression ratios and the two source lists, the indexer and its candidate stage, hyper-connections of 4 streams, 384 routed experts of which 6 are used with 1 shared, Engram before layers 1 and 14, and three DSpark blocks.
config · deepseek-ai/DeepSeek-V4.1-Flash / inference/config.json
Pinned revision 2cba9e42aa02 ↗ · lines 1–66
Read code excerpt
{
"vocab_size": 129280,
"dim": 5120,
"moe_inter_dim": 2304,
"n_layers": 40,
"n_mtp_layers": 3,
"dspark_block_size": 5,
"dspark_noise_token_id": 128799,
"dspark_target_layer_ids": [37, 38, 39],
"dspark_markov_rank": 256,
"dspark_n_routed_experts": 128,
"dspark_n_activated_experts": 3,
"n_heads": 64,
"n_routed_experts": 384,
"n_shared_experts": 1,
"n_activated_experts": 6,
"score_func": "sqrtsoftplus",
"route_scale": 1.5,
"swiglu_limit": 10.0,
"q_lora_rank": 1280,
"head_dim": 512,
"rope_head_dim": 64,
"norm_eps": 1e-20,
"o_groups": 8,
"o_lora_rank": 1024,
"window_size": 128,
"kv_source_layers": [2, 8, 14, 20],
"index_source_layers": [2, 8, 14, 20, 24, 28, 32, 36],
"original_seq_len": 65536,
"rope_theta": 10000,
"rope_factor": 16,
"beta_fast": 32,
"beta_slow": 1,
"index_n_heads": 32,
"index_head_dim": 128,
"index_topk": 512,
"candidate_source_layer": 20,
"candidate_topk_blocks": 2048,
"candidate_block_size": 8,
"hc_mult": 4,
"hc_sinkhorn_iters": 20,
"hc_eps": 1e-06,
"engram_layer_ids": [1, 14],
"engram_vocab_size": 16000000,
"engram_num_embeddings": [384006168, 384016682],
"engram_max_ngram_size": 4,
"engram_pad_id": 2,
"engram_compressed_vocab_size": 99092,
"dtype": "fp8",
"expert_dtype": "fp4",
"compress_rope_theta": 160000,
"compress_ratios": [0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
"vision_n_layers": 32,
"vision_dim": 1024,
"vision_n_heads": 16,
"vision_inter_dim": 2816,
"vision_patch_size": 14,
"vision_downsample_ratio": 3,
"vision_max_n_token": 1024,
"vision_min_pixels": 295936,
"vision_max_wh_ratio": null,
"image_token_id": 129264,
"engram_n_heads": 8,
"engram_head_dim": 256,
"vision_rope_theta": 10000
}