diff --git a/src/indexing/codecs/residual.jl b/src/indexing/codecs/residual.jl
index e1c4421..1afad7d 100644
--- a/src/indexing/codecs/residual.jl
+++ b/src/indexing/codecs/residual.jl
@@ -1,10 +1,25 @@
 using ..ColBERT: ColBERTConfig 
-using ProtoStructs
 
-@proto mutable struct ResidualCodec
+mutable struct ResidualCodec
     config::ColBERTConfig
     centroids::Matrix{Float64}
-    avg_residual:: Float64
+    avg_residual::Float64
     bucket_cutoffs::Vector{Float64}
     bucket_weights::Vector{Float64}
 end
+
+function compress_into_codes(codec::ResidualCodec, embs::Matrix{Float64})
+    codes = []
+
+    bsize = Int(floor((1 << 29) / size(codec.centroids)[2]))
+    offset = 1 
+    while (offset <= size(embs)[2])                             # batch on the second dimension
+        dot_products = transpose(embs[:, offset:min(size(embs)[2], offset + bsize - 1)]) * codec.centroids 
+        indices = (cartesian_index -> cartesian_index.I[2]).(argmax(dot_products, dims = 2)[:, 1])
+        append!(codes, indices)
+        offset += bsize
+    end
+
+    codes
+end
+