From 91cf8288aeace1e9031fb84bd75205af1bc91264 Mon Sep 17 00:00:00 2001
From: "Artem M. Chirkin" <9253178+achirkin@users.noreply.github.com>
Date: Wed, 19 Jul 2023 13:21:04 +0200
Subject: [PATCH] Hotfix: wrong constant in IVF-PQ fp_8bit2half

#1644 introduced a direct conversion from the custom ivf-pq fp8 type to half and a bug alongside. The exponent bias value wrong by one bit.
---
 cpp/include/raft/neighbors/detail/ivf_pq_fp_8bit.cuh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cpp/include/raft/neighbors/detail/ivf_pq_fp_8bit.cuh b/cpp/include/raft/neighbors/detail/ivf_pq_fp_8bit.cuh
index ca7eb4b7d9..68c8a513f6 100644
--- a/cpp/include/raft/neighbors/detail/ivf_pq_fp_8bit.cuh
+++ b/cpp/include/raft/neighbors/detail/ivf_pq_fp_8bit.cuh
@@ -116,7 +116,7 @@ struct fp_8bit {
       u &= ~1;  // zero the sign bit
     }
     half r;
-    constexpr uint16_t kBase16       = (0x7c00u | (0x0200u >> ValBits)) - (ExpMask << 10);
+    constexpr uint16_t kBase16       = (0x3c00u | (0x0200u >> ValBits)) - (ExpMask << 10);
     *reinterpret_cast<uint16_t*>(&r) = kBase16 + (u << (2u + ExpBits));
     if constexpr (Signed) {  // recover the sign bit
       if (v.bitstring & 1) { r = -r; }