From 792bb639960edbe1ad14884295a32869d4510abf Mon Sep 17 00:00:00 2001 From: Connor Olding Date: Wed, 27 Apr 2016 16:10:50 -0700 Subject: [PATCH] update readme --- README.md | 111 ++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 70 insertions(+), 41 deletions(-) diff --git a/README.md b/README.md index 5e4cb48..a02b218 100644 --- a/README.md +++ b/README.md @@ -1,18 +1,19 @@ # lips -An assembler for the MIPS R4300i architecture, written in Lua. +An assembler for the MIPS R4300i processor, written in Lua. This is not a 'true' assembler; it won't produce executable binary files. This was intended to assist in hacking N64 games. It does little more than output hex. -Not for production. Much of the code and syntax is untested and likely to change. +Not for production. +Much of the code and syntax is untested and likely to change. Even this README is incomplete. ## Usage -Copy the lips directory to somewhere Lua's `package.path` can find it. -If you're using it locally, you will need to write something like: +Install the lips directory to somewhere Lua's `package.path` can find it. +If you're using it locally, you'll either need to write something like: ``` package.path = package.path..";?/init.lua" ``` @@ -37,57 +38,85 @@ By default, lips will print the assembled word values in hex: etc... ``` +Other predefined output formats are available in [lips.writers]; +you can instantiate one and pass it through the second argument of lips. + Since lips is designed to assist with ROM/RAM hacking, it cannot produce executable files on its own. -Instead, it is meant to be integrated with an existing executable or memory dump. +Instead, it is meant to be integrated with +an existing executable or memory dump. For instance, consider [this injection routine][inject.lua] written for the Nintendo 64 Zelda games. +[writers]: https://github.com/notwa/lips/blob/master/lips/writers.lua [inject.lua]: https://github.com/notwa/mm/blob/master/Lua/inject.lua ## Syntax lips uses a derivative of [CajeASM's][caje] syntax. -It takes a couple notes from more traditional assemblers as well. +It takes a couple of notes from other assemblers as well. [caje]: https://github.com/Tarek701/CajeASM/ A run-down of various syntax elements: ```asm -// this is a comment +// this is a comment. /* this is a block comment */ -; this is a more traditional assembly style of comment -; we'll be using this so github's syntax highlighting doesn't blow up +; this is a more traditional assembly style of comment. +; we'll be using this so github's syntax highlighting doesn't blow up. -; this is comparible to C's #define my_const 0xDEADBEEF +; set a variable. these are inlined in the preprocessing stage. [my_const]: 0xDEADBEEF -; we can then use it in instructions by adding a @ prefix +; we can then use it in instructions by adding a @ prefix: li a0, @my_const -; whitespace is optional +; whitespace is optional. li a0,@myconst ; commas can be optional too, ; but this feature will likely be removed in the future. li a0 @myconst -; instruction/register names are case-insensitive, as are hex digits +; instructions may end in an extra comma; +; this may make mass-entry or generation of instructions easier. +li a0, @my_const, + +; instruction/register names are case-insensitive, as are hex digits. LI A0, @my_const LuI a0, 0xDeAd +; however, note that the 'x' in "0x" must be lowercase. +; the same applies for 0b and 0o for binary and octal, respectively. + ; coprocessor 0 registers are case-insensitive as well, ; though this may change in the future. mfc0 a1, CouNT -; labels are defined with a colon and referenced without prefix, as such: +; labels are defined with a colon, and referenced without a prefix, as such: my_label: b my_label nop + ; directives are prefixed with a dot. ; also, labels may be used in .word directives. .word my_label, 1, 2, 3, 0x4567 -; octal numbers are supported - .short 0177, 0404 + +; numbers may be written in eight different ways: two for each base. + li t1, 0xDEADBEEF + li t2, $DEADBEEF + li t3, %11011110101011011011111011101111 + li t4, 0b11011110101011011011111011101111 + li t5, 0o33653337357 + li t6, 033653337357 + li t7, 3735928559 + li t8, #3735928559 + +; though, as a stylistic choice, the preferred way of writing them are as such: + li t1, 0xDEADBEEF + li t4, 0b11011110101011011011111011101111 + li t5, 0o33653337357 + li t7, 3735928559 + .align ; implied argument of 2, for a 2**n=4 byte alignment -; loading and storing can be written in several ways (addressing modes) +; loading and storing can be written in several ways (addressing modes): lw s0, label lw s1, (s0) lw s2, 256(s0) @@ -95,16 +124,16 @@ my_label: sw s2, label+4 sw s3, label+4(s0) -; relative labels, borrowed from asw (except ours require a suffixing colon) --: - b ++ +; relative labels are borrowed from asw, except ours require a suffixing colon: +-: : #1 + b ++ ; branches to #3 nop +: --: - b -- +-: ; #2 + b -- ; branches to #1 nop -+: - b - ++: : #3 + b - ; branches to #2 nop ; TODO: more examples! @@ -112,7 +141,8 @@ my_label: ## Instructions -Instructions were primarily referenced from [the N64 Toolkit: Opcodes.][n64op] +Instructions were primarily referenced from [the N64 Toolkit: Opcodes][n64op] +and the [bass assembler.][basstables] An in-depth look at instructions for MIPS IV processors is given by [the MIPS IV Instruction Set manual.][mipsiv] @@ -120,36 +150,33 @@ Most of this applies to our MIPS III architecture. [The MIPS64 Instruction Set manual][mips64] is sometimes useful. Much of it doesn't apply to our older MIPS III architecture, -but it's a little cleaner than the older manual. +but it's a little cleaner than the older manuals. -There's also a brief and incomplete [overview of MIPS instructions.][overview] -First-time writers of MIPS assembly may find this the most useful. +Last, but not least, [the R4300i datasheet][r4300i] covers +some of the nuances of the processor. [n64op]: https://github.com/mikeryan/n64dev/tree/master/docs/n64ops +[basstables]: https://github.com/ARM9/bass/tree/master/bass/arch/table/mipseb [mipsiv]: http://www.cs.cmu.edu/afs/cs/academic/class/15740-f97/public/doc/mips-isa.pdf [mips64]: http://scc.ustc.edu.cn/zlsc/lxwycj/200910/W020100308600769158777.pdf -[overview]: http://www.mrc.uidaho.edu/mrc/people/jff/digital/MIPSir.html +[r4300i]: http://www.futuretech.blinkenlights.nl/R4300_datasheet.Rev0.3.pdf -### Unimplemented +### Unimplemented Instructions As far as I know, all native R4300i instructions have been implemented. Whether or not they output the proper machine code is another thing. ### Unimplemented Pseudo-Instructions -Besides implicit arguments for existing instructions, there are: +* MUL, DIV, REM -* ABS, MUL, DIV, REM - -* BGE, BLE, BLT, BGT - -* any Set (Condition) \[Immediate\] \[Unsigned\] pseudo-instructions +* many Set/Branch pseudo-instructions ## Registers In order of numerical value, with intended usage: -* R0: always zero; cannot be written to. 'zero' is an acceptable alias. +* R0: always zero; cannot be changed. 'zero' is an acceptable alias. * AT: assembler temporary. used by various pseudo-instructions. user may use freely if they're wary. @@ -224,7 +251,8 @@ defaults to 0x80000000. this allows you to have a PC value different from origin: `PC = origin + base` -* `.push {vars...}` `.pop {vars...}' +* `.push {vars...}` +`.pop {vars...}' pushes or pops variables with an internal stack. supported variables: org, base, pc. @@ -260,6 +288,7 @@ same as ascii, but with a null byte added to the end. ### Unimplemented -* FLOAT: writes a list of 32-bit floating point numbers until end-of-line. -this may not get implemented due to a lack of aliasing in vanilla Lua, -and thus accuracy issues. +* `.float {numbers..}` +`.double {numbers..}` +writes a list of 32-bit/64-bit floating point numbers until end-of-line. +this may not get implemented in vanilla Lua due to a lack of aliasing.