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Update tools.js

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Just a tweak really - re-ordered the zeroing-out checks in getFirmwareHash() to match the expected order of each section within the BIOS file. This may help to avoid a theoretical issue where bytes in user-substituted content (e.g., a boot logo) accidentally matches against some other blob of binary we're searching for using findSequence(). Doing the search-and-replace in the expected ordering should help to avoid that... I think? Won't hurt anyway!
This commit is contained in:
vonmillhausen 2023-10-09 20:20:54 +01:00
parent a87b80d577
commit 06d37840a6
1 changed files with 42 additions and 30 deletions
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72
tools/tools.js
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@ -12,6 +12,14 @@
Just like the tools themselves, this file should be considered CC0 Public
Domain (https://creativecommons.org/publicdomain/zero/1.0/)
Version 1.4: Re-ordered the getFirmwareHash() zeroing-out checks to match the
expected order to find them in in the BIOS file - just some future-proofing
in case some user-substituted content (e.g., a boot logo) happens to contain
bytes that a subsequent call to findSequence() might accidentally match. I
also added some comments with the rough location of each block within the
file, so if I have to add something else in the future I'll be able to slide
it into the right place :)
Version 1.3: Added support for blanking out the SNES audio bitrate and cycles
bits that `bnister` identified as a workaround for the "start-SNES-games-
twice" issue that cropped up in firmware versions after March
@ -68,40 +76,11 @@ function getFirmwareHash(data) {
dataCopy[398] = 0x00;
dataCopy[399] = 0x00;
// Next identify the boot logo position, and blank it out too...
var badExceptionOffset = findSequence([0x62, 0x61, 0x64, 0x5F, 0x65, 0x78, 0x63, 0x65, 0x70, 0x74, 0x69, 0x6F, 0x6E, 0x00, 0x00, 0x00], dataCopy);
if (badExceptionOffset > -1) {
var bootLogoStart = badExceptionOffset + 16;
for (var i = bootLogoStart; i < (bootLogoStart + 204800); i++) {
dataCopy[i] = 0x00;
}
}
else {
return false;
}
// Next identify the emulator button mappings (if they exist), and blank
// them out too...
var preButtonMapOffset = findSequence([0x00, 0x00, 0x00, 0x71, 0xDB, 0x8E, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], dataCopy);
if (preButtonMapOffset > -1) {
var postButtonMapOffset = findSequence([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00], dataCopy, preButtonMapOffset);
if (postButtonMapOffset > -1) {
for (var i = preButtonMapOffset + 16; i < postButtonMapOffset; i++) {
dataCopy[i] = 0x00;
}
}
else {
return false;
}
}
else {
return false;
}
// Next we'll look for (and zero out) the five bytes that the power
// monitoring functions of the SF2000 use for switching the UI's battery
// level indicator. These unfortunately can't be searched for - they're just
// in specific known locations for specific firmware versions...
// Location: Approximately 0x35A8F8 (about 25% of the way through the file)
var prePowerCurve = findSequence([0x11, 0x05, 0x00, 0x02, 0x24], dataCopy);
if (prePowerCurve > -1) {
var powerCurveFirstByteLocation = prePowerCurve + 5;
@ -159,9 +138,42 @@ function getFirmwareHash(data) {
return false;
}
// Next identify the emulator button mappings (if they exist), and blank
// them out too...
// Location: Approximately 0x8D6200 (about 75% of the way through the file)
var preButtonMapOffset = findSequence([0x00, 0x00, 0x00, 0x71, 0xDB, 0x8E, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], dataCopy);
if (preButtonMapOffset > -1) {
var postButtonMapOffset = findSequence([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00], dataCopy, preButtonMapOffset);
if (postButtonMapOffset > -1) {
for (var i = preButtonMapOffset + 16; i < postButtonMapOffset; i++) {
dataCopy[i] = 0x00;
}
}
else {
return false;
}
}
else {
return false;
}
// Next identify the boot logo position, and blank it out too...
// Location: Approximately 0x9B3520 (about 80% of the way through the file)
var badExceptionOffset = findSequence([0x62, 0x61, 0x64, 0x5F, 0x65, 0x78, 0x63, 0x65, 0x70, 0x74, 0x69, 0x6F, 0x6E, 0x00, 0x00, 0x00], dataCopy);
if (badExceptionOffset > -1) {
var bootLogoStart = badExceptionOffset + 16;
for (var i = bootLogoStart; i < (bootLogoStart + 204800); i++) {
dataCopy[i] = 0x00;
}
}
else {
return false;
}
// Next we'll look for and zero out the bytes used for SNES audio rate and
// CPU cycles, in case folks want to patch those bytes to correct SNES
// first-launch issues on newer firmwares...
// Location: Approximately 0xC0A170 (about 99% of the way through the file)
var preSNESBytes = findSequence([0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x80], dataCopy);
if (preSNESBytes > -1) {
var snesAudioBitrateBytes = preSNESBytes + 8;