Ahh, so now that I am more awake, here's what I check for each of the SYSEX. This is what works for my particular usage, You may or may not need the same.
I scan the file byte by byte, and a SYSEX event is found and flagged with F0. I then check the length byte, and from there further check the rest of the SYSEX to see if it a reset.
For GM1 System On and GM2 System On
// GM reset
// F0 7E 7F 09 01 F7 (GM1 hardware)
// F0 05 7E 7F 09 01 F7 (GM1 software)
// F0 7E 7F 09 03 F7 (GM2 hardware)
// F0 05 7E 7F 09 03 F7 (GM2 software)
case 0x05:
cur_pos = buffer_tell(global.edit_buffer);
if ((buffer_peek(global.edit_buffer, cur_pos, buffer_u8) == 0x7E) &&
(buffer_peek(global.edit_buffer, cur_pos + 1, buffer_u8) == 0x7F) &&
(buffer_peek(global.edit_buffer, cur_pos + 2, buffer_u8) == 0x09) &&
((buffer_peek(global.edit_buffer, cur_pos + 3, buffer_u8) == 0x01) || (buffer_peek(global.edit_buffer, cur_pos + 3, buffer_u8) == 0x03)) &&
(buffer_peek(global.edit_buffer, cur_pos + 4, buffer_u8) == 0xF7))
For Yamaha XG Reset
// Yamaha XG reset
// F0 43 (10) 4C 00 00 7E 00 F7 (hardware)
// F0 08 43 (10) 4C 00 00 7E 00 F7 (software)
case 0x08:
cur_pos = buffer_tell(global.edit_buffer);
if ((buffer_peek(global.edit_buffer, cur_pos, buffer_u8) == 0x43) &&
/*(buffer_peek(global.edit_buffer, cur_pos + 1, buffer_u8) == 0x10) &&*/
(buffer_peek(global.edit_buffer, cur_pos + 2, buffer_u8) == 0x4C) &&
(buffer_peek(global.edit_buffer, cur_pos + 3, buffer_u8) == 0x00) &&
(buffer_peek(global.edit_buffer, cur_pos + 4, buffer_u8) == 0x00) &&
(buffer_peek(global.edit_buffer, cur_pos + 5, buffer_u8) == 0x7E) &&
(buffer_peek(global.edit_buffer, cur_pos + 6, buffer_u8) == 0x00) &&
(buffer_peek(global.edit_buffer, cur_pos + 7, buffer_u8) == 0xF7))
And for Roland GS Reset
// GS reset
// F0 41 (10) 42 12 40 00 7F 00 41 F7 (hardware)
// F0 0A 41 (10) 42 12 40 00 7F 00 41 F7 (software)
case 0x0A:
cur_pos = buffer_tell(global.edit_buffer);
if ((buffer_peek(global.edit_buffer, cur_pos, buffer_u8) == 0x41) &&
/*(buffer_peek(global.edit_buffer, cur_pos + 1, buffer_u8) == 0x10) &&*/
(buffer_peek(global.edit_buffer, cur_pos + 2, buffer_u8) == 0x42) &&
(buffer_peek(global.edit_buffer, cur_pos + 3, buffer_u8) == 0x12) &&
(buffer_peek(global.edit_buffer, cur_pos + 4, buffer_u8) == 0x40) &&
(buffer_peek(global.edit_buffer, cur_pos + 5, buffer_u8) == 0x00) &&
(buffer_peek(global.edit_buffer, cur_pos + 6, buffer_u8) == 0x7F) &&
(buffer_peek(global.edit_buffer, cur_pos + 7, buffer_u8) == 0x00) &&
(buffer_peek(global.edit_buffer, cur_pos + 8, buffer_u8) == 0x41) &&
(buffer_peek(global.edit_buffer, cur_pos + 9, buffer_u8) == 0xF7))
The GM1 and GM2 System On do not specify a device.
The XG and GS DO specify a device ID of some sort. For my purposes, it is not relevant, so I check every byte except for the ID byte.
And finally, for the GS percussion channel assignment SYSEX.
Information about this can be found.... in the manual? I'll have to dig through my stuff when I have more time to see where I got it from. I just did a quick look through the SC-8850 manual but didn't see it, but I'm sure it's in there. SYSEX explanations start around page 229.
https://cdn.roland.com/assets/media/pdf/SC-8850_OM.pdf
// GS Custom Percussion Assignment
// F0 0A 41 (10) 42 12 [40 1A 15] [02] 0F F7
// [.. 1x ..] x = part# / (probably) ch# 1-9, 0, A-F
// [0y] y = type: 0 = standard, 1 = drum map 1, 2 = drum map 2
else if ((buffer_peek(global.edit_buffer, cur_pos, buffer_u8) == 0x41) &&
/*(buffer_peek(global.edit_buffer, cur_pos + 1, buffer_u8) == 0x10) &&*/
(buffer_peek(global.edit_buffer, cur_pos + 2, buffer_u8) == 0x42) &&
(buffer_peek(global.edit_buffer, cur_pos + 3, buffer_u8) == 0x12) &&
(buffer_peek(global.edit_buffer, cur_pos + 4, buffer_u8) == 0x40) &&
/*(buffer_peek(global.edit_buffer, cur_pos + 5, buffer_u8) == 0x00) &&*/
(buffer_peek(global.edit_buffer, cur_pos + 6, buffer_u8) == 0x15) &&
/*(buffer_peek(global.edit_buffer, cur_pos + 7, buffer_u8) == 0x00) &&*/
(buffer_peek(global.edit_buffer, cur_pos + 8, buffer_u8) == 0x0F) &&
(buffer_peek(global.edit_buffer, cur_pos + 9, buffer_u8) == 0xF7))
{
part_num = buffer_peek(global.edit_buffer, cur_pos + 5, buffer_u8);
part_num -= 0xF;
part_type = buffer_peek(global.edit_buffer, cur_pos + 7, buffer_u8);
global.custom_drums[part_num - 1] = part_type;
}