From 8f297be26fa7d0fdbdb4fe2dfefe10ecb13fc742 Mon Sep 17 00:00:00 2001 From: Claude Date: Sat, 30 May 2026 17:05:47 +0000 Subject: [PATCH] Vectorise bulk uint16 reads in the descriptor reader Add node_body_t::read_uint16_block: bounds-check the whole block once, then reconstruct each uint16 from its two little-endian bytes in a flat loop the compiler vectorises (a copy on little-endian hosts, a byte-swap on big-endian). The image reader's per-pixel decode_uint16 loop, whose per-element bounds check blocked vectorisation, was a large part of colour pakset load time; it now calls read_uint16_block. Bit-identical to the old loop; version-0 images keep their per-pixel player-colour fixup. --- src/simutrans/descriptor/reader/image_reader.cc | 10 ++-------- src/simutrans/descriptor/reader/obj_reader.h | 10 ++++++++++ 2 files changed, 12 insertions(+), 8 deletions(-) diff --git a/src/simutrans/descriptor/reader/image_reader.cc b/src/simutrans/descriptor/reader/image_reader.cc index bfd22da6f..fab9b68f2 100644 --- a/src/simutrans/descriptor/reader/image_reader.cc +++ b/src/simutrans/descriptor/reader/image_reader.cc @@ -81,11 +81,8 @@ obj_desc_t *image_reader_t::read_node(FILE *fp, obj_node_info_t &node) desc->imageid = IMG_EMPTY; skip_reading_pixels_if_no_graphics; - uint16* dest = desc->data; if (desc->h > 0) { - for (uint i = 0; i < desc->len; i++) { - *dest++ = decode_uint16(p); - } + p.read_uint16_block(desc->data, desc->len); } } else if(version==3) { @@ -99,11 +96,8 @@ obj_desc_t *image_reader_t::read_node(FILE *fp, obj_node_info_t &node) desc->imageid = IMG_EMPTY; skip_reading_pixels_if_no_graphics; - uint16* dest = desc->data; if (desc->h > 0) { - for (uint i = 0; i < desc->len; i++) { - *dest++ = decode_uint16(p); - } + p.read_uint16_block(desc->data, desc->len); } } else { diff --git a/src/simutrans/descriptor/reader/obj_reader.h b/src/simutrans/descriptor/reader/obj_reader.h index 050723fb5..ba7aec6e0 100644 --- a/src/simutrans/descriptor/reader/obj_reader.h +++ b/src/simutrans/descriptor/reader/obj_reader.h @@ -182,6 +182,16 @@ public: return complain(2); } + /// Bulk little-endian uint16 read: one bounds check then a flat loop, so + /// the compiler vectorises it (a per-element read_uint16 loop won't). + void read_uint16_block(uint16* dest, size_t count) + { + const uint8* src = (const uint8*)read_bytes(count * 2); + for (size_t i = 0; i < count; i++) { + dest[i] = (uint16)(src[2 * i] | (src[2 * i + 1] << 8)); + } + } + inline uint32 read_uint32() { if (ptr + 3 < end) { -- 2.54.0