This tool can be used to alter the boot logo on an SF2000 handheld gaming console. Please note this tool is provided as-is, and no support will be given if this corrupts your device's bios; make sure you have backups of anything you care about before messing with your device's critical files! 🙂
-
Step 1: Select Original bisrv.asd
@@ -99,47 +98,174 @@
var logoOffset; // Will contain the offset of the boot logo within the bisrv.asd file
var newLogoData; // Used to store the little-endian RGB565 binary data of the new boot logo
+ // Define a function that takes a Uint8Array and an optional offset and returns the index
+ // of the first match or -1 if not found...
+ function findSequence(needle, haystack, offset) {
+
+ // If offset is not provided, default to 0
+ offset = offset || 0;
+
+ // Loop through the data array starting from the offset
+ for (var i = offset; i < haystack.length - needle.length + 1; i++) {
+
+ // Assume a match until proven otherwise
+ var match = true;
+
+ // Loop through the target sequence and compare each byte
+ for (var j = 0; j < needle.length; j++) {
+
+ if (haystack[i + j] !== needle[j]) {
+ // Mismatch found, break the inner loop and continue the outer loop
+ match = false;
+ break;
+ }
+
+ }
+
+ // If match is still true after the inner loop, we have found a match
+ if (match) {
+
+ // Return the index of the first byte of the match
+ return i;
+
+ }
+ }
+
+ // If we reach this point, no match was found
+ return -1;
+ }
+
+ // Returns an SHA-256 hash of a given firmware (ignoring common user changes), or returns
+ // false on failure...
+ function getFirmwareHash(data) {
+
+ // Data should be a Uint8Array, which as an object is passed by reference... we're going
+ // to be manipulating that data before generating our hash, but we don't want to modify
+ // the original object at all... so we'll create a copy, and work only on the copy...
+ var dataCopy = data.slice();
+
+ // Only really worthwhile doing this for big bisrv.asd files...
+ if (dataCopy.length > 12640000) {
+ // First, replace CRC32 bits with 00...
+ dataCopy[396] = 0x00;
+ dataCopy[397] = 0x00;
+ 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;
+ }
+
+ // If we're here, we've zeroed-out all of the bits of the firmware that are
+ // semi-user modifiable (boot logo, button mappings and the CRC32 bits); now
+ // we can generate a hash of what's left and compare it against some known
+ // values...
+ return crypto.subtle.digest("SHA-256", dataCopy.buffer)
+ .then(function(digest) {
+ var array = Array.from(new Uint8Array(digest));
+ var hash = array.map(byte => ("00" + byte.toString(16)).slice(-2)).join("");
+ return hash;
+ })
+ .catch(function(error) {
+ return false;
+ });
+ }
+ else {
+ return false;
+ }
+ }
+
function bisrvLoad(file) {
var frBisrv = new FileReader();
+ frBisrv.readAsArrayBuffer(file);
frBisrv.onload = function(event) {
// Read the provided file's data into an array...
var data = new Uint8Array(event.target.result);
- // Let's check the data to see if it looks like one of the known bisrv.asd versions...
- if (data.length == 12647452) {
- // That's the correct length for the original March 28th version of the file
- logoOffset = 0x9B9030;
- bisrvData = data;
- document.getElementById("bisrvOutput").innerHTML = "INFO: March 28th bisrv.asd detected
";
- }
- else if (data.length == 12648068) {
- // That's the correct length for the April 20th version of the file
- logoOffset = 0x9B91D8;
- bisrvData = data;
- document.getElementById("bisrvOutput").innerHTML = "INFO: April 20th bisrv.asd detected
";
- }
- else if (data.length == 12656068) {
- // That's the correct length for the May 15th version of the file
- logoOffset = 0x9BB0B8;
- bisrvData = data;
- document.getElementById("bisrvOutput").innerHTML = "INFO: May 15th bisrv.asd detected
";
+ // We'll do a hash-check against it...
+ hashResult = getFirmwareHash(data);
+
+ // The result could be either a Promise if it had a bisrv.asd-like structure and we got
+ // a hash, or false otherwise... let's check!
+ if (hashResult instanceof Promise) {
+ // We got a Promise! Wait for it to finish so we get our bisrv.asd hash...
+ hashResult.then(function(dataHash) {
+ // Check the hash against all the known good ones...
+ switch (dataHash) {
+ // Mid-March BIOS...
+ case "4411143d3030adc442e99f7ac4e7772f300c844bbe10d639702fb3ba049a4ee1":
+ logoOffset = 0x9B9030;
+ bisrvData = data;
+ document.getElementById("bisrvOutput").innerHTML = "INFO: Mid-March bisrv.asd detected
";
+ break;
+
+ // April 20th BIOS...
+ case "b50e50aa4b1b1d41489586e989f09d47c4e2bc27c072cb0112f83e6bc04e2cca":
+ logoOffset = 0x9B91D8;
+ bisrvData = data;
+ document.getElementById("bisrvOutput").innerHTML = "INFO: April 20th bisrv.asd detected
";
+ break;
+
+ // May 15th BIOS...
+ case "d878a99d26242836178b452814e916bef532d05acfcc24d71baa31b8b6f38ffd":
+ logoOffset = 0x9BB0B8;
+ bisrvData = data;
+ document.getElementById("bisrvOutput").innerHTML = "INFO: May 15th bisrv.asd detected
";
+ break;
+
+ // May 22nd BIOS...
+ case "6aebab0e4da39e0a997df255ad6a1bd12fdd356cdf51a85c614d47109a0d7d07":
+ logoOffset = 0x9BB098;
+ bisrvData = data;
+ document.getElementById("bisrvOutput").innerHTML = "INFO: May 22nd bisrv.asd detected
";
+ break;
+
+ default:
+ // Huh... wasn't false so had bisrv.asd structure, but didn't return
+ // a known hash... a new BIOS version? Unknown anyway!
+ console.log(dataHash);
+ document.getElementById("bisrvOutput").innerHTML = "ERROR: While the file you've selected does appear to be generally structured like the SF2000's bisrv.asd BIOS file, the specifics of your file don't match any known SF2000 BIOS version. As such, this tool cannot modify the selected file.
";
+ return;
+ break;
+ }
+
+ // If we're here we've got a good file, so enable the input for step 2 (image selection)...
+ document.getElementById("imageSelector").removeAttribute("disabled");
+ });
}
else {
- document.getElementById("bisrvOutput").innerHTML = "ERROR: The selected file does not appear to be a known bisrv.asd file!
";
- document.getElementById("imageSelector").setAttribute("disabled", "");
- document.getElementById("downloadButton").setAttribute("disabled", "");
- bisrvData = undefined;
- logoOffset = undefined;
+ // We got false, so whatever it was, it wasn't a bisrv.asd...
+ document.getElementById("bisrvOutput").innerHTML = "ERROR: The file you've selected doesn't appear to have the same data structure as expected for a bisrv.asd file.
";
return;
}
-
- // If we're here we've got a good file, so enable the input for step 2 (image selection)...
- document.getElementById("imageSelector").removeAttribute("disabled");
};
-
- frBisrv.readAsArrayBuffer(file);
}
function imageLoad(file) {
@@ -271,6 +397,6 @@
}
- CC0: public domain. Version 1.1, 20230516.1
+ CC0: public domain. Version 1.2, 20230522.1