Hello fellow Robloxians!
Perhaps you can help me with a problem. Right now I'm working on Byte Spy v3 (you can check out v2 here: https://www.roblox.com/library/127231254/Byte-Spy-v2-0) which is much simpler and more efficient. I also plan on adding some new features. For those of you who do not know, it is a LASM (Lua assembly language, the Lua virtual machine language, output of string.dump) disassembler.
Right now I'm running into a problem adding double precision floating point to string converter into it. v2 didn't include it, so I can't just look at how I did it before. To test the functionality I've parsed a dump of the main parser function which has two numbers in it, 1 and 4, which are represented as floating points in the dump. Here is what they are:
0x 00 00 00 00 00 00 F0 3F
0x 00 00 00 00 00 00 10 40
I'm not sure which is 1 and which is 4, but I assume the bottom number is 1 since its raw value is smaller. Looking on Wikipedia (the source of all truth, despite what your English teacher said) at https://en.wikipedia.org/wiki/Double-precision_floating-point_format a 1 should look like:
0 01111111111 0000000000000000000000000000000000000000000000000000
Why does the 1 presented by dump and the 1 presented by Wikipedia differ? Is Roblox using a different floating point format than IEE 754?
For those that want it, here is the code (note, it is in a module, and starts at line 84):
return function(func)
func = string.dump(func)
func = setmetatable({func:byte(1, func:len())}, dump)
func.header = {
{name = "Header signiture", value = string.char(func:nextBytes(4))};
{name = "Version number", value = func:nextNumber(1)};
{name = "Format Version", value = func:nextNumber(1)};
{name = "Endianness flag", value = func:nextNumber(1)};
{name = "Size of int", value = func:nextNumber(1)};
{name = "Size of size_t", value = func:nextNumber(1)};
{name = "Size of Instruction", value = func:nextNumber(1)};
{name = "Size of lua_Number", value = func:nextNumber(1)};
{name = "Integral flag", value = func:nextNumber(1)};
}
return {
{name = "Header", value = func.header};
{name = "Main Function", value = func:nextChunk()};
}
end
And the output of Byte Spy v3:
[Header] = {
[Header signiture] = Lua
[Version number] = 81
[Format Version] = 0
[Endianness flag] = 1
[Size of int] = 4
[Size of size_t] = 4
[Size of Instruction] = 4
[Size of lua_Number] = 8
[Integral flag] = 0
}
[Main Function] = {
[Source Name] = "=Workspace.Parser"
[Line first defined] = 83
[Line last defined] = 101
[Number of upvalues] = 1
[Number of parameters] = 1
[Number of is_vararg flag] = 0
[Maximum stack size] = 14
[Instructions] = {
[0] = GETGLOBAL, 1, 0
[1] = GETTABLE, 1, 1, 257
[2] = MOVE, 2, 0
[3] = CALL, 1, 2, 2
[4] = MOVE, 0, 1
[5] = GETGLOBAL, 1, 2
[6] = NEWTABLE, 2, 0, 0
[7] = SELF, 3, 0, 259
[8] = LOADK, 5, 4
[9] = SELF, 6, 0, 261
[10] = CALL, 6, 2, 0
[11] = CALL, 3, 0, 0
[12] = SETLIST, 2, 0, 1
[13] = GETUPVAL, 3, 0
[14] = CALL, 1, 3, 2
[15] = MOVE, 0, 1
[16] = NEWTABLE, 1, 9, 0
[17] = NEWTABLE, 2, 0, 2
[18] = SETTABLE, 2, 263, 264
[19] = GETGLOBAL, 3, 0
[20] = GETTABLE, 3, 3, 266
[21] = SELF, 4, 0, 267
[22] = LOADK, 6, 12
[23] = CALL, 4, 3, 0
[24] = CALL, 3, 0, 2
[25] = SETTABLE, 2, 265, 3
[26] = NEWTABLE, 3, 0, 2
[27] = SETTABLE, 3, 263, 269
[28] = SELF, 4, 0, 270
[29] = LOADK, 6, 4
[30] = CALL, 4, 3, 2
[31] = SETTABLE, 3, 265, 4
[32] = NEWTABLE, 4, 0, 2
[33] = SETTABLE, 4, 263, 271
[34] = SELF, 5, 0, 270
[35] = LOADK, 7, 4
[36] = CALL, 5, 3, 2
[37] = SETTABLE, 4, 265, 5
[38] = NEWTABLE, 5, 0, 2
[39] = SETTABLE, 5, 263, 272
[40] = SELF, 6, 0, 270
[41] = LOADK, 8, 4
[42] = CALL, 6, 3, 2
[43] = SETTABLE, 5, 265, 6
[44] = NEWTABLE, 6, 0, 2
[45] = SETTABLE, 6, 263, 273
[46] = SELF, 7, 0, 270
[47] = LOADK, 9, 4
[48] = CALL, 7, 3, 2
[49] = SETTABLE, 6, 265, 7
[50] = NEWTABLE, 7, 0, 2
[51] = SETTABLE, 7, 263, 274
[52] = SELF, 8, 0, 270
[53] = LOADK, 10, 4
[54] = CALL, 8, 3, 2
[55] = SETTABLE, 7, 265, 8
[56] = NEWTABLE, 8, 0, 2
[57] = SETTABLE, 8, 263, 275
[58] = SELF, 9, 0, 270
[59] = LOADK, 11, 4
[60] = CALL, 9, 3, 2
[61] = SETTABLE, 8, 265, 9
[62] = NEWTABLE, 9, 0, 2
[63] = SETTABLE, 9, 263, 276
[64] = SELF, 10, 0, 270
[65] = LOADK, 12, 4
[66] = CALL, 10, 3, 2
[67] = SETTABLE, 9, 265, 10
[68] = NEWTABLE, 10, 0, 2
[69] = SETTABLE, 10, 263, 277
[70] = SELF, 11, 0, 270
[71] = LOADK, 13, 4
[72] = CALL, 11, 3, 2
[73] = SETTABLE, 10, 265, 11
[74] = SETLIST, 1, 9, 1
[75] = SETTABLE, 0, 262, 1
[76] = NEWTABLE, 1, 2, 0
[77] = NEWTABLE, 2, 0, 2
[78] = SETTABLE, 2, 263, 278
[79] = GETTABLE, 3, 0, 262
[80] = SETTABLE, 2, 265, 3
[81] = NEWTABLE, 3, 0, 2
[82] = SETTABLE, 3, 263, 279
[83] = SELF, 4, 0, 280
[84] = CALL, 4, 2, 2
[85] = SETTABLE, 3, 265, 4
[86] = SETLIST, 1, 2, 1
[87] = RETURN, 1, 2
[88] = RETURN, 0, 1
}
[Constants] = {
[0] = "string"
[1] = "dump"
[2] = "setmetatable"
[3] = "byte"
[4] = 330945 * 2^0
[5] = "len"
[6] = "header"
[7] = "name"
[8] = "Header signiture"
[9] = "value"
[10] = "char"
[11] = "nextBytes"
[12] = 99504 * 2^0
[13] = "Version number"
[14] = "nextNumber"
[15] = "Format Version"
[16] = "Endianness flag"
[17] = "Size of int"
[18] = "Size of size_t"
[19] = "Size of Instruction"
[20] = "Size of lua_Number"
[21] = "Integral flag"
[22] = "Header"
[23] = "Main Function"
[24] = "nextChunk"
}
[Prototypes] = {
}
[Source Line Positions] = {
[0] = 84
[1] = 84
[2] = 84
[3] = 84
[4] = 84
[5] = 85
[6] = 85
[7] = 85
[8] = 85
[9] = 85
[10] = 85
[11] = 85
[12] = 85
[13] = 85
[14] = 85
[15] = 85
[16] = 86
[17] = 86
[18] = 87
[19] = 87
[20] = 87
[21] = 87
[22] = 87
[23] = 87
[24] = 87
[25] = 87
[26] = 87
[27] = 88
[28] = 88
[29] = 88
[30] = 88
[31] = 88
[32] = 88
[33] = 89
[34] = 89
[35] = 89
[36] = 89
[37] = 89
[38] = 89
[39] = 90
[40] = 90
[41] = 90
[42] = 90
[43] = 90
[44] = 90
[45] = 91
[46] = 91
[47] = 91
[48] = 91
[49] = 91
[50] = 91
[51] = 92
[52] = 92
[53] = 92
[54] = 92
[55] = 92
[56] = 92
[57] = 93
[58] = 93
[59] = 93
[60] = 93
[61] = 93
[62] = 93
[63] = 94
[64] = 94
[65] = 94
[66] = 94
[67] = 94
[68] = 94
[69] = 95
[70] = 95
[71] = 95
[72] = 95
[73] = 95
[74] = 96
[75] = 96
[76] = 97
[77] = 97
[78] = 98
[79] = 98
[80] = 98
[81] = 98
[82] = 99
[83] = 99
[84] = 99
[85] = 99
[86] = 100
[87] = 100
[88] = 101
}
[Locals] = {
[0] = "func"
}
[Upvalues] = {
[0] = "dump"
}
}
1 comment
Have you considered that you're parsing the dump wrong?