From 52ac8d952fe7c722e33a3237e465dcf258076613 Mon Sep 17 00:00:00 2001 From: Rekai Musuka Date: Fri, 10 Mar 2023 00:00:48 -0600 Subject: [PATCH] chore: move Channel, Ringbuffer, rotr, sext impls to lib --- src/lib.zig | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 95 insertions(+), 2 deletions(-) diff --git a/src/lib.zig b/src/lib.zig index 86dc023..4df9855 100644 --- a/src/lib.zig +++ b/src/lib.zig @@ -1,6 +1,8 @@ const std = @import("std"); -pub fn RingBuffer(comptime T: type) type { +const Log2Int = std.math.Log2Int; + +pub fn Channel(comptime T: type) type { return struct { const Self = @This(); const Index = usize; @@ -8,7 +10,7 @@ pub fn RingBuffer(comptime T: type) type { const Atomic = std.atomic.Atomic; const max_capacity = (@as(Index, 1) << @typeInfo(Index).Int.bits - 1) - 1; // half the range of index type - const log = std.log.scoped(.RingBuffer); + const log = std.log.scoped(.Channel); read: Atomic(Index), write: Atomic(Index), @@ -67,3 +69,94 @@ pub fn RingBuffer(comptime T: type) type { } }; } + +pub fn RingBuffer(comptime T: type) type { + return struct { + const Self = @This(); + const Index = usize; + const max_capacity = (@as(Index, 1) << @typeInfo(Index).Int.bits - 1) - 1; // half the range of index type + + const log = std.log.scoped(.RingBuffer); + + read: Index, + write: Index, + buf: []T, + + const Error = error{buffer_full}; + + pub fn init(buf: []T) Self { + std.debug.assert(std.math.isPowerOfTwo(buf.len)); // capacity must be a power of two + std.debug.assert(buf.len <= max_capacity); + + std.mem.set(T, buf, 0); + + return .{ .read = 0, .write = 0, .buf = buf }; + } + + pub fn push(self: *Self, value: T) Error!void { + if (self.isFull()) return error.buffer_full; + defer self.write += 1; + + self.buf[self.mask(self.write)] = value; + } + + pub fn pop(self: *Self) ?T { + if (self.isEmpty()) return null; + defer self.read += 1; + + return self.buf[self.mask(self.read)]; + } + + /// Returns the number of entries read + pub fn copy(self: *const Self, cpy: []T) Index { + const count = std.math.min(self.len(), cpy.len); + var start: Index = self.read; + + for (cpy, 0..) |*v, i| { + if (i >= count) break; + + v.* = self.buf[self.mask(start)]; + start += 1; + } + + return count; + } + + fn len(self: *const Self) Index { + return self.write - self.read; + } + + fn isFull(self: *const Self) bool { + return self.len() == self.buf.len; + } + + fn isEmpty(self: *const Self) bool { + return self.read == self.write; + } + + fn mask(self: *const Self, idx: Index) Index { + return idx & (self.buf.len - 1); + } + }; +} + +// Sign-Extend value of type `T` to type `U` +pub fn sext(comptime T: type, comptime U: type, value: T) T { + // U must have less bits than T + comptime std.debug.assert(@typeInfo(U).Int.bits <= @typeInfo(T).Int.bits); + + const iT = std.meta.Int(.signed, @typeInfo(T).Int.bits); + const ExtU = if (@typeInfo(U).Int.signedness == .unsigned) T else iT; + const shift_amt = @intCast(Log2Int(T), @typeInfo(T).Int.bits - @typeInfo(U).Int.bits); + + return @bitCast(T, @bitCast(iT, @as(ExtU, @truncate(U, value)) << shift_amt) >> shift_amt); +} + +/// See https://godbolt.org/z/W3en9Eche +pub inline fn rotr(comptime T: type, x: T, r: anytype) T { + if (@typeInfo(T).Int.signedness == .signed) + @compileError("cannot rotate signed integer"); + + const ar = @intCast(Log2Int(T), @mod(r, @typeInfo(T).Int.bits)); + return x >> ar | x << (1 +% ~ar); +} \ No newline at end of file