101 lines
2.5 KiB
Zig
101 lines
2.5 KiB
Zig
const std = @import("std");
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const Log2Int = std.math.Log2Int;
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pub inline fn sext(comptime bits: comptime_int, value: u32) u32 {
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comptime std.debug.assert(bits <= 32);
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const amount = 32 - bits;
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return @bitCast(u32, @bitCast(i32, value << amount) >> amount);
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}
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/// See https://godbolt.org/z/W3en9Eche
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pub inline fn rotr(comptime T: type, x: T, r: anytype) T {
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if (@typeInfo(T).Int.signedness == .signed)
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@compileError("cannot rotate signed integer");
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const ar = @intCast(Log2Int(T), @mod(r, @typeInfo(T).Int.bits));
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return x >> ar | x << (1 +% ~ar);
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}
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pub const EmulatorFps = struct {
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const Self = @This();
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fps: u32,
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count: std.atomic.Atomic(u32),
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timer: std.time.Timer,
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pub fn init() Self {
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return .{
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.fps = 0,
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.count = std.atomic.Atomic(u32).init(0),
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.timer = std.time.Timer.start() catch unreachable,
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};
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}
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// TODO: Rename
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pub fn completeFrame(self: *Self) void {
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_ = self.count.fetchAdd(1, .Monotonic);
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}
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pub fn value(self: *Self) u32 {
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const expected = @intToFloat(f64, std.time.ns_per_s);
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const actual = @intToFloat(f64, self.timer.read());
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if (actual >= expected) {
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self.fps = self.count.swap(0, .SeqCst);
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self.timer.reset();
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}
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return self.fps;
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}
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};
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pub fn intToBytes(comptime T: type, value: anytype) [@sizeOf(T)]u8 {
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comptime std.debug.assert(@typeInfo(T) == .Int);
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var result: [@sizeOf(T)]u8 = undefined;
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var i: Log2Int(T) = 0;
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while (i < result.len) : (i += 1) result[i] = @truncate(u8, value >> i * @bitSizeOf(u8));
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return result;
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}
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/// The Title from the GBA Cartridge may be null padded to a maximum
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/// length of 12 bytes.
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///
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/// This function returns a slice of everything just before the first
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/// `\0`
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pub fn asString(title: [12]u8) []const u8 {
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var len = title.len;
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for (title) |char, i| {
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if (char == 0) {
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len = i;
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break;
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}
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}
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return title[0..len];
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}
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/// Copies a Title and returns either an identical or similar
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/// array consisting of ASCII that won't make any file system angry
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///
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/// e.g. POKEPIN R/S to POKEPIN R_S
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pub fn escape(title: [12]u8) [12]u8 {
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var result: [12]u8 = title;
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for (result) |*char| {
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if (char.* == '/' or char.* == '\\') char.* = '_';
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if (char.* == 0) break;
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}
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return result;
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}
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pub const FilePaths = struct {
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rom: []const u8,
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bios: ?[]const u8,
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save: ?[]const u8,
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};
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