520 lines
18 KiB
Rust
520 lines
18 KiB
Rust
use crate::ast::{Label, Scope, VASMLine};
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use crate::parse_error::AssembleError;
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use crate::vasm_evaluator::eval;
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use crate::vasm_preprocessor::{Line, LineSource};
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use std::collections::BTreeMap;
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/// This will solve all the .equ directives and return a symbol table of them.
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/// .equ directives must be able to be solved in order, that is, in terms of
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/// only preceding .equ directives. Anything else is an error.
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fn solve_equs(lines: &[VASMLine]) -> Result<Scope, AssembleError> {
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let mut scope: Scope = Scope::new();
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let line_nums: BTreeMap<usize, i32> = BTreeMap::new();
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for (line_idx, line) in lines.iter().enumerate() {
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let line_num = line_idx + 1;
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if let VASMLine::Equ(Label(name), expr) = line {
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let value = eval(expr, line_num, &line_nums, &scope)
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.map_err(|e| AssembleError::EquResolveError(line_num, name.to_string(), e))?;
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if let Some(_old_value) = scope.insert(name.clone(), value) {
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return Err(AssembleError::EquDuplicateError(line_num, name.to_string()));
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}
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}
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}
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Ok(scope)
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}
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type LineLengths = BTreeMap<usize, usize>;
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type LineAddresses = BTreeMap<usize, i32>;
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fn arg_length(val: i32) -> usize {
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if val < 0 {
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3
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} else if val < 256 {
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1
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} else if val < 65536 {
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2
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} else {
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3
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}
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}
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/// This figures out the instruction lengths. We'll do this naively; if we can't
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/// immediately tell that an instruction needs only a 0/1/2 byte argument (because it's
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/// a constant, or a .equ that we've solved, or something) then we'll assume it's a
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/// full 24-bit argument.
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///
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/// - Lines that don't represent output (.equ, .org, etc) have length 0
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/// - .db directives are either strings (set aside the length of the string), or
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/// numbers (set aside three bytes. If it's shorter than that it still may be a variable,
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/// which might grow to be larger).
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/// - Opcodes with no argument are 1 byte long.
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/// - Opcodes with an argument, if that argument is a constant or decidable solely with
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/// what we know right now (.equs), are however long that argument is. If we don't
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/// know right now (based on a label, say) then we'll set aside the full 3 bytes (so it's
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/// 4 bytes long, with the instruction byte).
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fn measure_instructions(lines: &[VASMLine], scope: &Scope) -> LineLengths {
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let line_nums: BTreeMap<usize, i32> = BTreeMap::new();
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let mut lengths = LineLengths::new();
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for (line_idx, line) in lines.iter().enumerate() {
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let line_num = line_idx + 1;
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match line {
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VASMLine::Instruction(_, _, None) => {
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lengths.insert(line_num, 1);
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}
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VASMLine::Instruction(_, _, Some(node)) => {
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let len = eval(node, line_num, &line_nums, scope).map_or(3, arg_length);
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lengths.insert(line_num, len + 1);
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}
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VASMLine::Db(_, _) => {
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lengths.insert(line_num, 3);
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}
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VASMLine::StringDb(_, value) => {
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lengths.insert(line_num, value.len());
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}
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VASMLine::Org(_, _) | VASMLine::Equ(_, _) | VASMLine::LabelDef(_) | VASMLine::Blank => {
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lengths.insert(line_num, 0);
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}
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VASMLine::Macro(_) => unreachable!(),
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}
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}
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lengths
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}
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/// Time to start placing labels. The tricky part here is the .org directives, which can have
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/// expressions as their arguments. We'll compromise a little bit and say that a .org directive
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/// can only refer to labels that precede it, so, you can use .orgs to generate (say) a jump table
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/// but still make it easy for me to figure out what refers to what.
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///
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/// We'll go through the lines, adding each one's length (calculated in measure_instructions) to it.
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/// If it has a label, we'll store that label's new value to the scope.
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///
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/// But, we'll skip labels that come before .equs: that would make every .equ set to its address,
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/// rather than the argument.
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fn place_labels(
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lines: &[VASMLine],
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scope: Scope,
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lengths: &LineLengths,
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) -> Result<(LineAddresses, Scope), AssembleError> {
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let mut scope = scope;
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let mut address = 0;
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let mut addresses = LineAddresses::new();
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for (line_idx, line) in lines.iter().enumerate() {
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let line_num = line_idx + 1;
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if let VASMLine::Org(_, expr) = line {
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address = eval(expr, line_num, &addresses, &scope)
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.map_err(|err| AssembleError::OrgResolveError(line_num, err))?;
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addresses.insert(line_num, address);
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}
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if let Some(Label(label)) = line.label() {
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if !scope.contains_key(label) {
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scope.insert(label.clone(), address as i32);
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}
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}
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match line {
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VASMLine::Org(_, _) => {}
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_ => {
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addresses.insert(line_num, address);
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address += *lengths.get(&line_num).unwrap_or(&0) as i32;
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}
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}
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}
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Ok((addresses, scope))
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}
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fn poke_word(code: &mut Vec<u8>, at: usize, word: i32) {
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let [low, mid, high, _] = word.to_le_bytes();
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code[at] = low;
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code[at + 1] = mid;
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code[at + 2] = high;
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}
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/// Find the lower and upper bounds where this program will place memory
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fn code_bounds(
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lines: &[VASMLine],
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line_addresses: &LineAddresses,
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line_lengths: &LineLengths,
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) -> Result<(usize, usize), AssembleError> {
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let mut actual_lines = lines
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.iter()
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.enumerate()
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.filter(|(_, line)| !line.zero_length());
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let (first_idx, _) = actual_lines.next().ok_or(AssembleError::NoCode)?;
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let start = line_addresses[&(first_idx + 1)] as usize;
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let actual_lines = lines
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.iter()
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.enumerate()
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.filter(|(_, line)| !line.zero_length());
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let (last_idx, _) = actual_lines.last().unwrap();
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let end = line_addresses[&(last_idx + 1)] as usize;
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let end_length = line_lengths[&(last_idx + 1)];
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Ok((start, end + end_length - 1))
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}
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/// Turn an iterable of strs into an assembled binary. This supports macros, but not
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/// the `#include` macro. The resulting Vec is only as large as it needs to be; if your
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/// code starts with `.org 0x400` and is five bytes long then the Vec will be five
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/// bytes long and index 0 will represent 0x400.
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/// ```
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/// assert_eq!(
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/// vasm::assemble_snippet(vec![".org 0x400", "push 5", "add 7"]),
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/// Ok(vec![0x01, 0x05, 0x05, 0x07])
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/// )
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/// ```
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pub fn assemble_snippet<'a, T: IntoIterator<Item = &'a str>>(
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lines: T,
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) -> Result<Vec<u8>, AssembleError> {
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let mut line_results: Vec<Result<Line, AssembleError>> =
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LineSource::new("_snippet", lines, |_file| {
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Err(AssembleError::IncludeError(
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0,
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"Including is not supported in assembling snippets".to_string(),
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))
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})
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.collect();
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if let Some(Err(error)) = line_results.iter().find(|line| line.is_err()) {
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Err(error.clone())
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} else {
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generate_code(
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line_results
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.iter_mut()
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.map(|line| line.clone().unwrap().line),
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)
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}
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}
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/// At this point all lines have addresses and lengths, and all arguments are reduced to
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/// numeric constants. It's time to generate code.
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///
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/// - Make an array of zeroes, length (end - start)
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/// - Go through the list of instructions, generating code for them:
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/// - .db instructions turn into byte values starting at `address - start`
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/// - Opcodes turn into instruction bytes at `address - start` followed (maybe) by
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/// arguments.
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/// - .orgs cause us to skip ahead some in the output
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///
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/// The instruction bytes are formed of six bits defining the instruction followed by two
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/// bits denoting how many bytes of argument follow it.
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///
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/// Vulcan is a little-endian architecture: multi-byte arguments / .dbs will store the
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/// least-significant byte at the lowest address, then the more significant bytes following.
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fn generate_code<T: IntoIterator<Item = VASMLine>>(lines: T) -> Result<Vec<u8>, AssembleError> {
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let lines: Vec<VASMLine> = lines.into_iter().collect();
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let scope = solve_equs(&lines)?;
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let line_lengths = measure_instructions(&lines, &scope);
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let (line_addresses, scope) = place_labels(&lines, scope, &line_lengths)?;
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let (start, end) = code_bounds(&lines, &line_addresses, &line_lengths)?;
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let mut code = vec![0u8; end - start + 1];
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let mut current_addr = start;
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for (line_idx, line) in lines.iter().enumerate() {
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let line_num = line_idx + 1;
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match line {
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VASMLine::Instruction(_, opcode, None) => {
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code[current_addr - start] = u8::from(*opcode) << 2;
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current_addr += 1;
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}
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VASMLine::Instruction(_, opcode, Some(arg)) => {
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let arg = eval(arg, line_num, &line_addresses, &scope)
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.map_err(|err| AssembleError::ArgError(line_num, err))?;
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let len = line_lengths[&line_num] - 1;
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let instr = (u8::from(*opcode) << 2) + len as u8;
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code[current_addr - start] = instr;
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let [low, mid, high, _] = arg.to_le_bytes();
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code[current_addr - start + 1] = low;
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if len > 1 {
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code[current_addr - start + 2] = mid
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}
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if len > 2 {
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code[current_addr - start + 3] = high
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}
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current_addr += len + 1;
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}
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VASMLine::Db(_, arg) => {
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let arg = eval(arg, line_num, &line_addresses, &scope)
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.map_err(|err| AssembleError::ArgError(line_num, err))?;
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poke_word(&mut code, current_addr - start, arg);
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current_addr += 3;
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}
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VASMLine::StringDb(_, string) => {
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for ch in string.as_bytes() {
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code[current_addr - start] = *ch;
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current_addr += 1;
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}
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}
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VASMLine::Org(_, _) => {
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current_addr = line_addresses[&(line_num + 1)] as usize;
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}
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VASMLine::Equ(_, _) | VASMLine::LabelDef(_) | VASMLine::Blank => {}
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VASMLine::Macro(_) => unreachable!(),
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}
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}
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Ok(code)
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}
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#[cfg(test)]
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mod test {
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use super::AssembleError::*;
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use super::*;
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use crate::ast::VASMLine;
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use crate::parse_error;
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use crate::parse_error::EvalError::*;
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use crate::vasm_parser::parse_vasm_line;
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fn parse<'a, T: IntoIterator<Item = &'a str>>(lines: T) -> Vec<VASMLine> {
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lines
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.into_iter()
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.map(|line| parse_vasm_line(line).unwrap())
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.collect()
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}
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fn place_labels_pass<'a, T: IntoIterator<Item = &'a str>>(
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lines: T,
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) -> Result<(LineAddresses, Scope), AssembleError> {
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let parsed_lines = parse(lines);
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let scope = solve_equs(&parsed_lines).unwrap();
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let lengths = measure_instructions(&parsed_lines, &scope);
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place_labels(&parsed_lines, scope, &lengths)
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}
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fn bounds<'a, T: IntoIterator<Item = &'a str>>(
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lines: T,
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) -> Result<(usize, usize), AssembleError> {
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let parsed_lines = parse(lines);
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let scope = solve_equs(&parsed_lines).unwrap();
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let lengths = measure_instructions(&parsed_lines, &scope);
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let (line_addresses, _scope) = place_labels(&parsed_lines, scope, &lengths)?;
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code_bounds(&parsed_lines, &line_addresses, &lengths)
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}
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#[test]
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fn test_equs() {
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assert_eq!(
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solve_equs(&parse(["blah: .equ 5+3"])),
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Ok([("blah".to_string(), 8)].into())
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);
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assert_eq!(
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solve_equs(&parse(["blah: .equ 5", "foo: .equ 3"])),
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Ok([("blah".to_string(), 5), ("foo".to_string(), 3)].into())
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);
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assert_eq!(
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solve_equs(&parse(["blah: .equ 5", "foo: .equ blah + 7"])),
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Ok([("blah".to_string(), 5), ("foo".to_string(), 12)].into())
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);
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assert_eq!(
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solve_equs(&parse(["add", "blah: .equ 5"])),
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Ok([("blah".to_string(), 5)].into())
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);
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}
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#[test]
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fn test_unsolvable_equs() {
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assert_eq!(
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solve_equs(&parse(["blah: .equ 5", "foo: .equ banana"])),
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Err(EquResolveError(
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2,
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"foo".into(),
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MissingLabel("banana".into())
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))
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);
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assert_eq!(
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solve_equs(&parse(["blah: .equ foo+3", "foo: .equ 7"])),
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Err(EquResolveError(
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1,
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"blah".into(),
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MissingLabel("foo".into())
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))
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);
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assert_eq!(
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solve_equs(&parse(["blah: .equ 3", "blah: .equ 7"])),
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Err(EquDuplicateError(2, "blah".into()))
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);
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}
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#[test]
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fn test_lengths() {
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assert_eq!(
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measure_instructions(
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&parse(["add", "add 1", "add 500", "add 70000", "add -7"]),
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&[].into()
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),
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[(1, 1), (2, 2), (3, 3), (4, 4), (5, 4)].into()
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);
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assert_eq!(
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measure_instructions(&parse([".db 7", ".db \"hello\\0\""]), &[].into()),
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[(1, 3), (2, 6)].into()
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);
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assert_eq!(
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measure_instructions(&parse([".org 256", "blah:", "foo: .equ 7"]), &[].into()),
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[(1, 0), (2, 0), (3, 0)].into()
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);
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assert_eq!(
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measure_instructions(
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&parse([".org 0x400", "push 3", "call blah", "hlt", "blah: mul 2"]),
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&[].into()
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),
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[(1, 0), (2, 2), (3, 4), (4, 1), (5, 2)].into()
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);
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assert_eq!(
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measure_instructions(
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&parse(["add 2 + foo", "add 3 + blah", "jmpr @foo"]),
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&[("blah".to_string(), 300)].into()
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),
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[(1, 4), (2, 3), (3, 4)].into()
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);
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}
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#[test]
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fn test_place_labels() {
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assert_eq!(
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place_labels_pass(["start: .org 256", "add", "dup"]),
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Ok((
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[(1, 256), (2, 256), (3, 257)].into(),
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[("start".to_string(), 256)].into()
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))
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);
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assert_eq!(
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place_labels_pass(["push 70000", "dup"]),
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Ok(([(1, 0), (2, 4)].into(), [].into()))
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);
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assert_eq!(
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place_labels_pass(["start: .equ 256", "blah: .org start + 4", "add"]),
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Ok((
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[(1, 0), (2, 260), (3, 260)].into(),
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[("blah".to_string(), 260), ("start".to_string(), 256)].into()
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))
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);
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assert_eq!(
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place_labels_pass(["start: .org 256", "blah: .org start + 10", "add"]),
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Ok((
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[(1, 256), (2, 266), (3, 266)].into(),
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[("blah".to_string(), 266), ("start".to_string(), 256)].into()
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))
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);
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assert_eq!(
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place_labels_pass([
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".org 1024",
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"nop 3",
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"call blah",
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"hlt",
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"blah: mul 2",
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"ret"
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]),
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Ok((
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[
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(1, 1024),
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(2, 1024),
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(3, 1026),
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(4, 1030),
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(5, 1031),
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(6, 1033)
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]
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.into(),
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[("blah".to_string(), 1031)].into()
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))
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);
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}
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#[test]
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fn test_unresolvable_orgs() {
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assert_eq!(
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place_labels_pass([".org 0xffffff - blah"]),
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Err(OrgResolveError(1, MissingLabel("blah".into())))
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);
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assert_eq!(
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place_labels_pass(["blah: .org blah"]),
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Err(OrgResolveError(1, MissingLabel("blah".into())))
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);
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}
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#[test]
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fn test_bounds() {
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assert_eq!(bounds(["add"]), Ok((0, 0)));
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assert_eq!(bounds(["add -4"]), Ok((0, 3)));
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assert_eq!(bounds(["add 7"]), Ok((0, 1)));
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assert_eq!(bounds([".org 0x400", "add"]), Ok((1024, 1024)));
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assert_eq!(
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bounds(["start: .equ 1024", ".org start", "add"]),
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Ok((1024, 1024))
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);
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assert_eq!(
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bounds([".org 0x400", "add", ".org 0x800"]),
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Ok((1024, 1024))
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);
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assert_eq!(
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bounds([".org 0x400", "add", ".org 0x800", ".db 5", "blah:"]),
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Ok((1024, 2050))
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);
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assert_eq!(bounds([]), Err(AssembleError::NoCode));
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assert_eq!(bounds([".org 0x400"]), Err(AssembleError::NoCode));
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assert_eq!(
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bounds(["foo: .equ 3", ".org 0x400"]),
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Err(AssembleError::NoCode)
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);
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}
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#[test]
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fn test_generate_code() {
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assert_eq!(generate_code(parse(["add"])), Ok(vec![4]));
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|
assert_eq!(
|
|
generate_code(parse([".org 0x400", "add 7"])),
|
|
Ok(vec![5, 7])
|
|
);
|
|
assert_eq!(generate_code(parse([".db 57"])), Ok(vec![57, 0, 0]));
|
|
assert_eq!(generate_code(parse([".db \"AZ\0\""])), Ok(vec![65, 90, 0]));
|
|
}
|
|
|
|
#[test]
|
|
fn test_assemble_snippet() {
|
|
assert_eq!(assemble_snippet(["add"]), Ok(vec![4]));
|
|
assert_eq!(
|
|
assemble_snippet(["apple"]),
|
|
Err(ParseError(
|
|
1,
|
|
parse_error::ParseError::InvalidInstruction("apple".into())
|
|
))
|
|
);
|
|
|
|
assert_eq!(
|
|
assemble_snippet(
|
|
".org 0x400
|
|
nop 3
|
|
call blah
|
|
hlt
|
|
blah: mul 2
|
|
ret"
|
|
.lines()
|
|
),
|
|
Ok(vec![
|
|
0x01, 0x03, // nop 3
|
|
0x67, 0x07, 0x04, 0x00, // call blah (arg defaults to 3 bytes long)
|
|
0x74, // hlt
|
|
0x0d, 0x02, // mul 2
|
|
0x68
|
|
])
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn test_relative_blanks() {
|
|
assert_eq!(assemble_snippet(".org 0x400
|
|
nop $+2
|
|
|
|
nop 0x111111
|
|
nop 0x222222".lines()),
|
|
Ok(vec![
|
|
0x03, 0x08, 0x04, 0x00,
|
|
0x03, 0x11, 0x11, 0x11,
|
|
0x03, 0x22, 0x22, 0x22
|
|
]))
|
|
}
|
|
}
|