| // Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import 'dart:ffi'; |
| |
| import 'package:ffi/ffi.dart'; |
| import 'package:expect/expect.dart'; |
| |
| /// typedef struct { |
| /// unsigned int bold : 1; |
| /// unsigned int underline : 2; |
| /// unsigned int italic : 1; |
| /// unsigned int blink : 1; |
| /// unsigned int reverse : 1; |
| /// unsigned int strike : 1; |
| /// unsigned int font : 4; |
| /// } ScreenCellAttrs; |
| class ScreenCellAttrs extends Struct { |
| @Int16() |
| external int bits; |
| |
| int get bold => getBits(kBoldFieldOffset, kBoldFieldLength); |
| void set bold(int value) => |
| setBits(kBoldFieldOffset, kBoldFieldLength, value); |
| |
| int get underline => getBits(kUnderlineFieldOffset, kUnderlineFieldLength); |
| void set underline(int value) => |
| setBits(kUnderlineFieldOffset, kUnderlineFieldLength, value); |
| |
| int get italic => getBits(kItalicFieldOffset, kItalicFieldLength); |
| void set italic(int value) => |
| setBits(kItalicFieldOffset, kItalicFieldLength, value); |
| |
| int get blink => getBits(kBlinkFieldOffset, kBlinkFieldLength); |
| void set blink(int value) => |
| setBits(kBlinkFieldOffset, kBlinkFieldLength, value); |
| |
| int get reverse => getBits(kReverseFieldOffset, kReverseFieldLength); |
| void set reverse(int value) => |
| setBits(kReverseFieldOffset, kReverseFieldLength, value); |
| |
| int get strike => getBits(kStrikeFieldOffset, kStrikeFieldLength); |
| void set strike(int value) => |
| setBits(kStrikeFieldOffset, kStrikeFieldLength, value); |
| |
| int get font => getBits(kFontFieldOffset, kFontFieldLength); |
| void set font(int value) => |
| setBits(kFontFieldOffset, kFontFieldLength, value); |
| |
| int getBits(int offset, int length) => bits.getBits(offset, length); |
| |
| void setBits(int offset, int length, int value) { |
| bits = bits.setBits(offset, length, value); |
| } |
| } |
| |
| const int kBoldFieldOffset = 0; |
| const int kBoldFieldLength = 1; |
| const int kUnderlineFieldOffset = kBoldFieldOffset + kBoldFieldLength; |
| const int kUnderlineFieldLength = 2; |
| const int kItalicFieldOffset = kUnderlineFieldOffset + kUnderlineFieldLength; |
| const int kItalicFieldLength = 1; |
| const int kBlinkFieldOffset = kItalicFieldOffset + kItalicFieldLength; |
| const int kBlinkFieldLength = 1; |
| const int kReverseFieldOffset = kBlinkFieldOffset + kBlinkFieldLength; |
| const int kReverseFieldLength = 1; |
| const int kStrikeFieldOffset = kReverseFieldOffset + kReverseFieldLength; |
| const int kStrikeFieldLength = 1; |
| const int kFontFieldOffset = kStrikeFieldOffset + kStrikeFieldLength; |
| const int kFontFieldLength = 4; |
| |
| /// Extension to use a 64-bit integer as bit field. |
| extension IntBitField on int { |
| static int _bitMask(int offset, int lenght) => ((1 << lenght) - 1) << offset; |
| |
| /// Read `length` bits at `offset`. |
| /// |
| /// Truncates everything. |
| int getBits(int offset, int length) { |
| final mask = _bitMask(offset, length); |
| return (this & mask) >> offset; |
| } |
| |
| /// Returns a new integer value in which `length` bits are overwritten at |
| /// `offset`. |
| /// |
| /// Truncates everything. |
| int setBits(int offset, int length, int value) { |
| final mask = _bitMask(offset, length); |
| return (this & ~mask) | ((value << offset) & mask); |
| } |
| } |
| |
| main() { |
| final p = allocate<ScreenCellAttrs>(count: 3); |
| |
| // Zeroes out all fields. |
| p.ref.bits = 0; |
| |
| // Set individual fields. |
| p.ref.blink = 0; |
| p.ref.bold = 1; |
| p.ref.font = 15; |
| p.ref.italic = 1; |
| p.ref.reverse = 0; |
| p.ref.strike = 0; |
| p.ref.underline = 2; |
| |
| // Read individual fields. |
| print(p.ref.blink); |
| print(p.ref.bold); |
| print(p.ref.font); |
| print(p.ref.italic); |
| print(p.ref.reverse); |
| print(p.ref.strike); |
| print(p.ref.underline); |
| |
| // A check for automated testing. |
| Expect.equals(1933, p.ref.bits); |
| |
| free(p); |
| } |