zba/src/util.zig

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const std = @import("std");
const Log2Int = std.math.Log2Int;
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pub inline fn sext(comptime bits: comptime_int, value: u32) u32 {
comptime std.debug.assert(bits <= 32);
const amount = 32 - bits;
return @bitCast(u32, @bitCast(i32, value << amount) >> amount);
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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 {
if (@typeInfo(T).Int.signedness == .signed)
@compileError("cannot rotate signed integer");
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const ar = @intCast(Log2Int(T), @mod(r, @typeInfo(T).Int.bits));
return x >> ar | x << (1 +% ~ar);
}
pub const FpsAverage = struct {
const Self = @This();
total: u64,
sample_count: u64,
pub fn init() Self {
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return .{ .total = 0, .sample_count = 1 };
}
pub fn add(self: *Self, sample: u64) void {
if (self.sample_count == 600) return self.reset(sample);
self.total += sample;
self.sample_count += 1;
}
pub fn calc(self: *const Self) f64 {
return @intToFloat(f64, std.time.ns_per_s) / (@intToFloat(f64, self.total) / @intToFloat(f64, self.sample_count));
}
fn reset(self: *Self, sample: u64) void {
self.total = sample;
self.sample_count = 1;
}
};
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pub fn intToBytes(comptime T: type, value: anytype) [@sizeOf(T)]u8 {
comptime std.debug.assert(@typeInfo(T) == .Int);
var result: [@sizeOf(T)]u8 = undefined;
var i: Log2Int(T) = 0;
while (i < result.len) : (i += 1) result[i] = @truncate(u8, value >> i * @bitSizeOf(u8));
return result;
}
/// The Title from the GBA Cartridge may be null padded to a maximum
/// length of 12 bytes.
///
/// This function returns a slice of everything just before the first
/// `\0`
pub fn correctTitle(title: [12]u8) []const u8 {
var len = title.len;
for (title) |char, i| {
if (char == 0) {
len = i;
break;
}
}
return title[0..len];
}
/// Copies a Title and returns either an identical or similar
/// array consisting of ASCII that won't make any file system angry
///
/// e.g. POKEPIN R/S to POKEPIN R_S
pub fn safeTitle(title: [12]u8) [12]u8 {
var result: [12]u8 = title;
for (result) |*char| {
if (char.* == '/' or char.* == '\\') char.* = '_';
if (char.* == 0) break;
}
return result;
}
pub fn fixTitle(alloc: std.mem.Allocator, title: [12]u8) ![]u8 {
var len: usize = 12;
for (title) |char, i| {
if (char == 0) {
len = i;
break;
}
}
const buf = try alloc.alloc(u8, len);
std.mem.copy(u8, buf, title[0..len]);
return buf;
}