From a4f175ac61a35da989e9e92591d807fd1d5afcd6 Mon Sep 17 00:00:00 2001
From: mehbark <terezi@pyrope.net>
Date: Tue, 25 Jun 2024 15:36:33 -0400
Subject: [PATCH] some specialization, not rly faster tho :(

---
 bf.zig | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 70 insertions(+), 5 deletions(-)

diff --git a/bf.zig b/bf.zig
index 0506b5e..a4d68ce 100644
--- a/bf.zig
+++ b/bf.zig
@@ -23,6 +23,10 @@ const Level1 = union(enum) {
     loop_start: u24,
     loop_end: u24,
 
+    zero,
+    find_zero_left,
+    find_zero_right,
+
     const Self = @This();
 
     fn pointless(self: Self) bool {
@@ -54,10 +58,16 @@ const Level1 = union(enum) {
             .out => |n| try writer.print("OUT {d: >4}", .{n}),
             .loop_start => |n| try writer.print("JEZ {d:0>4}", .{n}),
             .loop_end => |n| try writer.print("JNZ {d:0>4}", .{n}),
+            .zero => try writer.print("ZER     ", .{}),
+            .find_zero_left => try writer.print("FZL     ", .{}),
+            .find_zero_right => try writer.print("FZR     ", .{}),
         }
     }
 };
 
+// mandelbrot.b has 120 instances of [-] which can be replaced with a memory[mp] = 0
+// dang it! gcc -O3 with code generated by dbf2c.b finishes in like 1.4s
+
 // we'll do the discarding of comment chars here
 fn compileLevel1(allocator: mem.Allocator, src: []const u8) !ArrayList(Level1) {
     var cur = Level1.nothing();
@@ -67,8 +77,14 @@ fn compileLevel1(allocator: mem.Allocator, src: []const u8) !ArrayList(Level1) {
         out.deinit();
         openers.deinit();
     }
+    var skip: u8 = 0;
+
+    for (src, 0..) |b, i| {
+        if (skip > 0) {
+            skip -= 1;
+            continue;
+        }
 
-    for (src) |b| {
         switch (b) {
             '+', '-' => {
                 const n: i8 = if (b == '+') 1 else -1;
@@ -92,8 +108,19 @@ fn compileLevel1(allocator: mem.Allocator, src: []const u8) !ArrayList(Level1) {
             },
             '[' => {
                 if (!cur.pointless()) try out.append(cur);
-                cur = .{ .loop_start = 0 };
-                try openers.append(@as(u24, @truncate(out.items.len)));
+                // bad (what if space yk)
+                if ((src[i + 1] == '-' or src[i + 1] == '+') and src[i + 2] == ']') {
+                    try out.append(.zero);
+                    skip = 2;
+                    cur = Level1.nothing();
+                } else if ((src[i + 1] == '>' or src[i + 1] == '<') and src[i + 2] == ']') {
+                    try out.append(if (src[i + 1] == '>') .find_zero_right else .find_zero_left);
+                    skip = 2;
+                    cur = Level1.nothing();
+                } else {
+                    cur = .{ .loop_start = 0 };
+                    try openers.append(@as(u24, @truncate(out.items.len)));
+                }
             },
             ']' => {
                 if (!cur.pointless()) try out.append(cur);
@@ -203,8 +230,35 @@ test "level 1" {
             .{ .loop_end = 0 },
         },
     );
-    testLevel1("bla bla - [ ++ ", &[_]Level1{}) catch |err| try testing.expectEqual(err, error.UnclosedOpener);
-    testLevel1("wow wow += ]", &[_]Level1{}) catch |err| try testing.expectEqual(err, error.UnopenedCloser);
+
+    testLevel1(
+        "bla bla - [ ++ ",
+        &[_]Level1{},
+    ) catch |err| try testing.expectEqual(err, error.UnclosedOpener);
+    testLevel1(
+        "wow wow += ]",
+        &[_]Level1{},
+    ) catch |err| try testing.expectEqual(err, error.UnopenedCloser);
+
+    try testLevel1(
+        "+++[>>[-]-+]",
+        &[_]Level1{
+            .{ .inc = 3 },
+            .{ .loop_start = 4 },
+            .{ .shift = 2 },
+            .zero,
+            .{ .loop_end = 1 },
+        },
+    );
+
+    try testLevel1(
+        "[>][<][-]",
+        &[_]Level1{
+            .find_zero_right,
+            .find_zero_left,
+            .zero,
+        },
+    );
 }
 
 pub fn main() !void {
@@ -263,6 +317,17 @@ pub fn main() !void {
             .loop_end => |new_ip| {
                 if (memory[mp] != 0) ip = new_ip;
             },
+            .zero => memory[mp] = 0,
+            .find_zero_right => {
+                while (memory[mp] != 0) {
+                    mp +%= 1;
+                }
+            },
+            .find_zero_left => {
+                while (memory[mp] != 0) {
+                    mp -%= 1;
+                }
+            },
         }
         ip += 1;
     }