shithub: libdraw-zig

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slightly update the protocol handling (ease of use)

--- a/src/libdraw.zig

+++ b/src/libdraw.zig

@@ -29,8 +29,7 @@

         var id: u32 = 0;

         var trys: usize = 0;

         while (trys < 25) : (trys += 1) {

-            var bs = try d.bufImage(1 + 4 + 4 + 4 + 1);

-            var a = bs.writer();

+            var a = try d.allocBuf(1 + 4 + 4 + 4 + 1);

             screenid += 1;

             id = screenid & 0xffff; // old devdraw bug

             a.writeByte('A') catch unreachable;

@@ -56,8 +55,7 @@

     pub fn lineop(dst: *Image, p0: Point, p1: Point, end0: u32, end1: u32, radius: u32, src: *Image, sp: Point, op: DrawOp) !void {

         const d = dst.display;

         try d.setDrawOp(op);

-        var bs = try d.bufImage(1 + 4 + 2 * 4 + 2 * 4 + 4 + 4 + 4 + 4 + 2 * 4);

-        var a = bs.writer();

+        var a = try d.allocBuf(1 + 4 + 2 * 4 + 2 * 4 + 4 + 4 + 4 + 4 + 2 * 4);

         a.writeByte('L') catch unreachable;

         a.writeIntLittle(u32, dst.id) catch unreachable;

         a.writeIntLittle(u32, p0.x) catch unreachable;

@@ -75,8 +73,7 @@

         const d = dst.display;

         try d.setDrawOp(op);

-        var bs = try d.bufImage(1 + 4 + 4 + 4 + 4 * 4 + 2 * 4 + 2 * 4);

-        var a = bs.writer();

+        var a = try d.allocBuf(1 + 4 + 4 + 4 + 4 * 4 + 2 * 4 + 2 * 4);

         const s = src orelse d.black;

         const m = mask orelse d.@"opaque";

         a.writeByte('d') catch unreachable;

@@ -233,6 +230,7 @@

     _isnewdisplay: bool,

     screen: ?*Image = null,

     _screen: ?*Screen = null,

+    abpos: usize = 0, // for use in the writer

     pub fn init(ally: std.mem.Allocator, options: struct { devdir: []const u8 = "/dev", windir: []const u8 = "/dev" }) !*Display {

         const NINFO = 12 * 12;

         var info: [NINFO + 1]u8 = undefined;

@@ -352,8 +350,7 @@

         if (depth == 0) {

             return error.BadChanDesc;

         }

-        var bs = try self.bufImage(1 + 4 + 4 + 1 + 4 + 1 + 4 * 4 + 4 * 4 + 4);

-        var a = bs.writer();

+        var a = try self.allocBuf(1 + 4 + 4 + 1 + 4 + 1 + 4 * 4 + 4 * 4 + 4);

         self.imageid += 1;

         const id = self.imageid;

         // start writing the protocol

@@ -395,8 +392,7 @@

             return error.ImageNameTooLong;

         }

         self.flushImage(false) catch {};

-        var bs = try self.bufImage(1 + 4 + 1 + name.len);

-        var a = bs.writer();

+        var a = try self.allocBuf(1 + 4 + 1 + name.len);

         self.imageid += 1;

         const id = self.imageid;

         a.writeByte('n') catch unreachable;

@@ -455,8 +451,7 @@

         return im;

     }

     fn freeRemote(self: *Display, id: u32, t: enum { image, screen }) !void {

-        var bs = try self.bufImage(1 + 4);

-        const a = bs.writer();

+        var a = try self.allocBuf(1 + 4);

         const c: u8 = if (t == .image) 'f' else 'F';

         a.writeByte(c) catch unreachable;

         a.writeIntLittle(u32, id) catch unreachable;

@@ -479,7 +474,30 @@

         }

         try d.freeRemote(image.id, .image);

     }

-    pub fn bufImage(self: *Display, n: usize) !std.io.FixedBufferStream([]u8) {

+    const AllocedBuf = struct {

+        buffer: []u8,

+        pos: *usize,

+        fn writer(self: AllocedBuf) std.io.Writer(AllocedBuf, error{}, write) {

+            return .{ .context = self };

+        }

+        fn write(self: AllocedBuf, bytes: []const u8) error{}!usize {

+            if (bytes.len == 0) return 0;

+            if (self.pos.* >= self.buffer.len) unreachable; // we don't allocate more than we use

+

+            const n = if (self.pos.* + bytes.len <= self.buffer.len)

+                bytes.len

+            else

+                self.buffer.len - self.pos.*;

+

+            @memcpy(self.buffer[self.pos.*..][0..n], bytes[0..n]);

+            self.pos.* += n;

+

+            if (n == 0) unreachable;

+

+            return n;

+        }

+    };

+    pub fn allocBuf(self: *Display, n: usize) !std.io.Writer(AllocedBuf, error{}, AllocedBuf.write) {

         if (n > self.bufsize) {

             return error.BadCountBufSize;

         }

@@ -488,7 +506,9 @@

         }

         const p = self.bufp;

         self.bufp += n;

-        return std.io.fixedBufferStream(p[0..n]);

+        self.abpos = 0;

+        var ab = AllocedBuf{ .buffer = p[0..n], .pos = &self.abpos };

+        return ab.writer();

     }

     pub fn flush(self: *Display) !void {

         const n: i64 = @intCast(@intFromPtr(self.bufp) - @intFromPtr(self.buf.ptr));

@@ -582,8 +602,7 @@

     }

     pub fn setDrawOp(self: *Display, op: DrawOp) !void {

         if (op != .soverD) {

-            var bs = try self.bufImage(1 + 1);

-            var a = bs.writer();

+            var a = try self.allocBuf(1 + 1);

             a.writeByte('O') catch unreachable;

             a.writeByte(@intFromEnum(op)) catch unreachable;

         }