83 lines
2.4 KiB
Zig
83 lines
2.4 KiB
Zig
//brainf
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const std = @import("std");
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const io = std.io;
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const fs = std.fs;
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const process = std.process;
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pub fn main() !void {
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var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
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var allocator = arena.allocator();
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defer arena.deinit();
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var out = io.getStdOut().writer();
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var in = io.getStdIn().reader();
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var args = process.args();
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defer args.deinit();
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_ = args.skip();
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const prog_path = args.next() orelse {
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try io.getStdErr().writer().writeAll("i need a program path :(\n");
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process.exit(1);
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};
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var prog_file = try fs.cwd().openFile(prog_path, .{});
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const prog_unfiltered = try prog_file.readToEndAlloc(allocator, 1 << 24);
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var prog = try allocator.alloc(u8, prog_unfiltered.len);
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var prog_len: u32 = 0;
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for (prog_unfiltered) |c| {
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if (c == '+' or c == '-' or c == '>' or c == '<' or c == '[' or c == ']' or c == '.' or c == ',') {
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prog[prog_len] = c;
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prog_len += 1;
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}
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}
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var mem = try allocator.alloc(u8, 1 << 16);
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for (mem) |*m| {
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m.* = 0;
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}
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var mp: u16 = 0;
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var ip: u32 = 0;
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while (ip < prog_len) {
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switch (prog[ip]) {
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'+' => mem[mp] +%= 1,
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'-' => mem[mp] -%= 1,
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'>' => mp +%= 1,
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'<' => mp -%= 1,
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'[' => {
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if (mem[mp] == 0) {
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var depth: i16 = 1;
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ip += 1;
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while (depth > 0) : (ip += 1) {
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depth += switch (prog[ip]) {
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']' => -1,
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'[' => 1,
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else => 0,
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};
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}
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ip -= 1;
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}
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},
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']' => {
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if (mem[mp] != 0) {
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var depth: i16 = 1;
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ip -= 1;
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while (depth > 0) : (ip -= 1) {
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depth += switch (prog[ip]) {
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'[' => -1,
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']' => 1,
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else => 0,
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};
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}
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ip += 1;
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}
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},
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'.' => try out.writeByte(mem[mp]),
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',' => mem[mp] = in.readByte() catch 0,
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else => unreachable,
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}
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ip += 1;
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}
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}
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