From fbe833d515879fac589e2ae056bc8db424a6d060 Mon Sep 17 00:00:00 2001
From: Balazs Komuves <bkomuves@gmail.com>
Date: Thu, 13 Nov 2025 20:11:31 +0100
Subject: [PATCH] update the Nim parser too

---
 nim/circom_witnessgen/graph.nim |  5 +++++
 nim/circom_witnessgen/load.nim  | 33 +++++++++++++++++++++++++++++++--
 nim/main.nim                    | 15 +++++++++++++--
 3 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/nim/circom_witnessgen/graph.nim b/nim/circom_witnessgen/graph.nim
index 12e9ef0..c438550 100644
--- a/nim/circom_witnessgen/graph.nim
+++ b/nim/circom_witnessgen/graph.nim
@@ -86,9 +86,14 @@ type
 
   CircuitInputs* = seq[(string, SignalDescription)]
 
+  Prime* = object
+    primeNumber*: BigUInt
+    primeName*:   string
+
   GraphMetaData* = object
     witnessMapping*: WitnessMapping
     inputSignals*:   CircuitInputs  
+    prime*: Prime
 
   Graph* = object
     nodes*: seq[Node[uint32]]
diff --git a/nim/circom_witnessgen/load.nim b/nim/circom_witnessgen/load.nim
index 6be2935..07d340a 100644
--- a/nim/circom_witnessgen/load.nim
+++ b/nim/circom_witnessgen/load.nim
@@ -195,17 +195,46 @@ proc parseCircuitInput(buf: openArray[byte], p: var int): (string, SignalDescrip
   p = nextp
   return (name,desc)
 
+proc parsePrime(buf: openArray[byte], p: var int): Prime = 
+
+  # prime number (BigUInt)
+  let fld1 = buf.parseProtoField(p, LEN)
+  assert( fld1 == 3 , "expecting protobuf field id 3")
+  let len1 = buf.parseVarInt(p)
+  let nextp1 = p + len1
+  # protobuf is stupid, it's like triple wrapped
+  let fld1b = buf.parseProtoField(p, LEN)
+  assert( fld1b == 1 , "expecting protobuf field id 1")
+  let len1b = buf.parseVarInt(p)
+  var bytes: seq[byte] = newSeq[byte](len1b)
+  for i in 0..<len1b: bytes[i] = buf[p+i]
+  let number = BigUInt(bytes: bytes)
+  p = nextp1
+
+  # prime name (string)
+  let fld2 = buf.parseProtoField(p, LEN)
+  assert( fld2 == 4 , "expecting protobuf field id 4")
+  let len2 = buf.parseVarInt(p)
+  let nextp2 = p + len2
+  let bs = buf[p..<p+len2]
+  let name = bytesToString(bs)
+  p = nextp2
+ 
+  return Prime(primeNumber: number, primeName: name)
+
 proc parseMeta(buf: openArray[byte]): GraphMetaData = 
   var p: int = 0
 
   let mapping = buf.parseWitnessMapping(p)
 
   var entries: seq[(string, SignalDescription)] = newSeq[(string, SignalDescription)](0)
-  while(p < buf.len):
+  while(p < buf.len and buf[p]==0x12):
     let entry = buf.parseCircuitInput(p)
     entries.add(entry)
 
-  return GraphMetaData(witnessMapping: WitnessMapping(mapping: mapping), inputSignals: entries)
+  let prime = buf.parsePrime(p)
+
+  return GraphMetaData(witnessMapping: WitnessMapping(mapping: mapping), inputSignals: entries, prime: prime)
 
 #-------------------------------------------------------------------------------
 
diff --git a/nim/main.nim b/nim/main.nim
index 21ce4da..b665f81 100644
--- a/nim/main.nim
+++ b/nim/main.nim
@@ -1,4 +1,7 @@
 
+import circom_witnessgen/field
+# import circom_witnessgen/div_mod
+
 import circom_witnessgen/load
 import circom_witnessgen/input_json
 import circom_witnessgen/witness
@@ -12,6 +15,13 @@ const wtns_file:  string = "../tmp/nim3.wtns"
 
 #-------------------------------------------------------------------------------
 
+#[
+when isMainModule:
+
+  debugDivMod()  
+  # divModSanityCheck()
+]#
+
 when isMainModule:
 
   echo "loading in " & input_file
@@ -20,8 +30,9 @@ when isMainModule:
 
   echo "loading in " & graph_file
   let gr = loadGraph(graph_file)
-  # echo $gr
+  echo $gr
 
   echo "generating witness"
   let wtns = generateWitness( gr, inp )
-  exportWitness(wtns_file, wtns)
\ No newline at end of file
+  exportWitness(wtns_file, wtns)
+