init

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "asdf"
+version = "0.1.0"
+dependencies = [
+ "split_one",
+]
+
+[[package]]
+name = "split_one"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2198b215a5ce931043797f707249b3142fe544aca13cfbdf92bdaecccd7f214c"

Cargo.toml

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+[package]
+name = "asdf"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+split_one = "1.0.2"

src/main.rs

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+use std::time::{SystemTime, UNIX_EPOCH};
+
+const NANOS_PER_SEC: u32 = 1_000_000_000;
+fn manual_duration_as_secs_f32(secs: u64, nanos: u128) -> f32 {
+    let secs_as_f32 = secs as f32;
+    println!("secs_as_f32: {secs_as_f32:.10}");
+    let nanos_as_f32 = nanos as f32;
+    println!("nanos_as_f32: {nanos_as_f32:.10}");
+    let nanos_per_sec_as_f32 = NANOS_PER_SEC as f32;
+    println!("nanos_per_sec_as_f32: {nanos_per_sec_as_f32:.10}");
+    let nanos_in_seconds = nanos_as_f32 / nanos_per_sec_as_f32;
+    println!("nanos_in_seconds: {nanos_in_seconds:.10}");
+    let result = secs_as_f32 + nanos_in_seconds;
+    println!("result: {result:.10}");
+    result
+}
+
+fn manual_duration_as_secs_f32_late_cast(secs: u64, nanos: u128) -> f32 {
+    let nanos_in_seconds = nanos / (NANOS_PER_SEC as u128);
+    println!("nanos_in_seconds: {nanos_in_seconds:.10}");
+    let result = (secs as u128) + nanos_in_seconds;
+    println!("result: {result:.10}");
+    result as f32
+}
+
+fn main() {
+    let original = 1713441059 as u128;
+    let original_as_f32 = 1713441059 as f32;
+    println!("original: {original}");
+    println!("original_as_f32: {original_as_f32}");
+    println!("original_as_f32 < f32::MAX: {}", original_as_f32 < f32::MAX);
+    println!(
+        "original_as_f32 as u128 == original: {}",
+        original_as_f32 as u128 == original
+    );
+
+    let now = SystemTime::now();
+    println!("SystemTime::now(): {now:?}");
+    let now = now.duration_since(UNIX_EPOCH).unwrap();
+    println!("now.duration_since(): {now:?}");
+    let secs = now.as_secs();
+    let nanos = now.as_nanos() - ((secs * (NANOS_PER_SEC as u64)) as u128);
+    println!("now.duration_since() internal: Secs: {secs}, Nanos: {nanos}");
+    let now_f32 = now.as_secs_f32();
+    println!("as secs f32: {now_f32:.0}");
+    let now_f64 = now.as_secs_f64();
+    println!("as secs f64: {now_f64:.0}");
+    println!("secs: {secs:.10}");
+    println!("nanos: {nanos:.10}");
+    println!("NANOS_PER_SEC: {NANOS_PER_SEC:.10}");
+    let manual_f32 = manual_duration_as_secs_f32(secs, nanos);
+    println!("manual as secs f32: {manual_f32:.0}");
+    let manual_f32_late_cast = manual_duration_as_secs_f32_late_cast(secs, nanos);
+    println!("manual as secs f32 (late cast): {manual_f32_late_cast:.0}");
+}