zig-glfw/src/time.zig
2021-11-22 12:59:11 -07:00

129 lines
4.1 KiB
Zig

const std = @import("std");
const c = @import("c.zig").c;
const Error = @import("errors.zig").Error;
const getError = @import("errors.zig").getError;
const internal_debug = @import("internal_debug.zig");
/// Returns the GLFW time.
///
/// This function returns the current GLFW time, in seconds. Unless the time
/// has been set using @ref glfwSetTime it measures time elapsed since GLFW was
/// initialized.
///
/// This function and @ref glfwSetTime are helper functions on top of glfw.getTimerFrequency
/// and glfw.getTimerValue.
///
/// The resolution of the timer is system dependent, but is usually on the order
/// of a few micro- or nanoseconds. It uses the highest-resolution monotonic
/// time source on each supported platform.
///
/// @return The current time, in seconds, or zero if an
/// error occurred.
///
/// @thread_safety This function may be called from any thread. Reading and
/// writing of the internal base time is not atomic, so it needs to be
/// externally synchronized with calls to @ref glfwSetTime.
///
/// see also: time
pub inline fn getTime() f64 {
internal_debug.assertInitialized();
const time = c.glfwGetTime();
getError() catch unreachable; // Only error 'GLFW_NOT_INITIALIZED' is impossible
return time;
}
/// Sets the GLFW time.
///
/// This function sets the current GLFW time, in seconds. The value must be a positive finite
/// number less than or equal to 18446744073.0, which is approximately 584.5 years.
///
/// This function and @ref glfwGetTime are helper functions on top of glfw.getTimerFrequency and
/// glfw.getTimerValue.
///
/// @param[in] time The new value, in seconds.
///
/// Possible errors include glfw.Error.NotInitialized and glfw.Error.InvalidValue.
///
/// The upper limit of GLFW time is calculated as `floor((2^64 - 1) / 10^9)` and is due to
/// implementations storing nanoseconds in 64 bits. The limit may be increased in the future.
///
/// @thread_safety This function may be called from any thread. Reading and writing of the internal
/// base time is not atomic, so it needs to be externally synchronized with calls to glfw.getTime.
///
/// see also: time
pub inline fn setTime(time: f64) error{ InvalidValue }!void {
internal_debug.assertInitialized();
c.glfwSetTime(time);
getError() catch |err| return switch (err) {
// TODO: Consider whether to use GLFW error handling, or assert that 'time' is a valid value
Error.InvalidValue => err,
else => unreachable,
};
}
/// Returns the current value of the raw timer.
///
/// This function returns the current value of the raw timer, measured in `1/frequency` seconds. To
/// get the frequency, call glfw.getTimerFrequency.
///
/// @return The value of the timer, or zero if an error occurred.
///
/// @thread_safety This function may be called from any thread.
///
/// see also: time, glfw.getTimerFrequency
pub inline fn getTimerValue() u64 {
internal_debug.assertInitialized();
const value = c.glfwGetTimerValue();
getError() catch unreachable; // Only error 'GLFW_NOT_INITIALIZED' is impossible
return value;
}
/// Returns the frequency, in Hz, of the raw timer.
///
/// This function returns the frequency, in Hz, of the raw timer.
///
/// @return The frequency of the timer, in Hz, or zero if an error occurred.
///
/// @thread_safety This function may be called from any thread.
///
/// see also: time, glfw.getTimerValue
pub inline fn getTimerFrequency() u64 {
internal_debug.assertInitialized();
const frequency = c.glfwGetTimerFrequency();
getError() catch unreachable; // Only error 'GLFW_NOT_INITIALIZED' is impossible
return frequency;
}
test "getTime" {
const glfw = @import("main.zig");
try glfw.init(.{});
defer glfw.terminate();
_ = getTime();
}
test "setTime" {
const glfw = @import("main.zig");
try glfw.init(.{});
defer glfw.terminate();
_ = try glfw.setTime(1234);
}
test "getTimerValue" {
const glfw = @import("main.zig");
try glfw.init(.{});
defer glfw.terminate();
_ = glfw.getTimerValue();
}
test "getTimerFrequency" {
const glfw = @import("main.zig");
try glfw.init(.{});
defer glfw.terminate();
_ = glfw.getTimerFrequency();
}