From 352605c1b5af4ff2fa6e792a47b6f6451c1f4be8 Mon Sep 17 00:00:00 2001 From: tgsm Date: Sat, 21 Aug 2021 20:03:29 -0400 Subject: Add nitrobanner tool This tool was made from reverse-engineering the Nitro SDK's makebanner, and is intended to replace that program. It has been tested to match the Diamond/Pearl banners as well as the HeartGold/SoulSilver banners. --- tools/nitrobanner/crc16.cpp | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 tools/nitrobanner/crc16.cpp (limited to 'tools/nitrobanner/crc16.cpp') diff --git a/tools/nitrobanner/crc16.cpp b/tools/nitrobanner/crc16.cpp new file mode 100644 index 00000000..bac64b57 --- /dev/null +++ b/tools/nitrobanner/crc16.cpp @@ -0,0 +1,22 @@ +#include +#include "banner.h" +#include "crc16.h" + +u16 CalculateCRC16FromBannerData(const u8* banner_data) { + const std::array crc_table = { + 0x0000, 0xCC01, 0xD801, 0x1400, + 0xF001, 0x3C00, 0x2800, 0xE401, + 0xA001, 0x6C00, 0x7800, 0xB401, + 0x5000, 0x9C01, 0x8801, 0x4400, + }; + + u16 checksum = 0xFFFF; + + const std::size_t data_size = sizeof(Banner) - offsetof(Banner, bitmap); + for (std::size_t i = 0; i < data_size; i++) { + u16 lookup_index = crc_table[banner_data[i] & 0xF] ^ (checksum >> 4) ^ crc_table[checksum & 0xF]; + checksum = crc_table[banner_data[i] >> 4] ^ (lookup_index >> 4) ^ crc_table[lookup_index & 0xF]; + } + + return checksum; +} -- cgit v1.2.3