From 60b71d9f78895d78a641b1109e2b0ca293835698 Mon Sep 17 00:00:00 2001
From: Jonas Knobloch <jonas.knobloch@t-online.de>
Date: Sat, 4 Apr 2026 22:14:02 +0200
Subject: Add score method

---
 gpt2/cmd/gpt2/main.go | 77 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 74 insertions(+), 3 deletions(-)

(limited to 'gpt2/cmd')

diff --git a/gpt2/cmd/gpt2/main.go b/gpt2/cmd/gpt2/main.go
index cad3333..6c7a46b 100644
--- a/gpt2/cmd/gpt2/main.go
+++ b/gpt2/cmd/gpt2/main.go
@@ -3,26 +3,97 @@ package main
 import (
 	"fmt"
 	"log"
+	"math"
+	"slices"
 
 	"go.jknobloc.com/x/gpt2"
 )
 
 func main() {
-	prompt := []int64{464, 2068, 7586, 21831}
+	prompt := []int64{464, 2068, 7586}
 
-	m := gpt2.NewModel("gpt2/models/base/model.onnx", "0", gpt2.NewDefaultConfig())
+	generate(prompt) // [-13.483142 -11.277906]
+	score(prompt)    // [-13.48314 -11.277912]
+
+	_ = prompt
+}
+
+func generate(prompt []int64) {
+	m := gpt2.NewModel("gpt2/models/mbpe_conv/gpt2_8192_m000_babylm_v2/model_cache.onnx", "0", gpt2.NewDefaultConfig().WithVocabSize(8193), true, false)
 
 	if err := m.Init(); err != nil {
 		log.Fatal(err)
 	}
 
-	if out, err := m.Generate(prompt, 5, nil); err != nil {
+	logits := make([][]float32, 0)
+
+	if out, err := m.Generate(prompt, 0, &logits); err != nil {
 		log.Fatal(err)
 	} else {
 		fmt.Printf("\n%v\n", out)
 	}
 
+	fmt.Println(selectLogProbs(logits[:len(logits)-1], prompt[1:]))
+
+	if err := m.Destroy(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func score(prompt []int64) {
+	m := gpt2.NewModel("gpt2/models/mbpe_conv/gpt2_8192_m000_babylm_v2/model_eval.onnx", "0", gpt2.NewDefaultConfig().WithVocabSize(8193), false, true)
+
+	if err := m.Init(); err != nil {
+		log.Fatal(err)
+	}
+
+	logProbs := make([]float32, 0, 2)
+
+	if err := m.Score(prompt, &logProbs); err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println(logProbs)
+
 	if err := m.Destroy(); err != nil {
 		log.Fatal(err)
 	}
 }
+
+func selectLogProbs(logits [][]float32, tokens []int64) []float32 {
+	if len(logits) != len(tokens) {
+		panic("length mismatch")
+	}
+
+	r := make([]float32, len(tokens))
+
+	for i, token := range tokens {
+		logprobs := logSoftmax(logits[i])
+
+		r[i] = logprobs[token]
+	}
+
+	return r
+}
+
+func logSoftmax(logits []float32) []float32 {
+	m := slices.Max(logits)
+
+	s := float32(0.0)
+	r := make([]float32, len(logits))
+
+	for i, v := range logits {
+		e := float32(math.Exp(float64(v - m)))
+
+		r[i] = v
+		s += e
+	}
+
+	lse := float32(math.Log(float64(s))) + m
+
+	for i := range r {
+		r[i] -= lse
+	}
+
+	return r
+}
-- 
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