bigint::monty: simplify redc return value

cuviper · cuviper · commit 7fa27b60073b · 2017-10-22T15:36:33.000-07:00
diff --git a/bigint/src/monty.rs b/bigint/src/monty.rs
@@ -81,14 +81,13 @@ fn monty_redc(a: BigUint, mr: &MontyReducer) -> BigUint {
 
     // 4: R <- C * β^(-n)
     // This is an n-word bitshift, equivalent to skipping n words.
-    let r : Vec<u32> = c.iter().skip(n_size).cloned().collect();
-    let ret = BigUint::new(r);
+    let ret = BigUint::new(c[n_size..].to_vec());
 
     // 5: if R >= β^n then return R-N else return R.
     if &ret < mr.p {
         ret
     } else {
-        &ret-mr.p
+        ret - mr.p
     }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -81,14 +81,13 @@ fn monty_redc(a: BigUint, mr: &MontyReducer) -> BigUint {`
`81`	`81`
`82`	`82`	`// 4: R <- C * β^(-n)`
`83`	`83`	`// This is an n-word bitshift, equivalent to skipping n words.`
`84`		`- let r : Vec<u32> = c.iter().skip(n_size).cloned().collect();`
`85`		`- let ret = BigUint::new(r);`
	`84`	`+ let ret = BigUint::new(c[n_size..].to_vec());`
`86`	`85`
`87`	`86`	`// 5: if R >= β^n then return R-N else return R.`
`88`	`87`	`if &ret < mr.p {`
`89`	`88`	`ret`
`90`	`89`	`} else {`
`91`		`- &ret-mr.p`
	`90`	`+ ret - mr.p`
`92`	`91`	`}`
`93`	`92`	`}`
`94`	`93`