From 5eb795731a57c4403c9d6a9bd1eb2c5586e9a0f7 Mon Sep 17 00:00:00 2001
From: Tom French <tom@tomfren.ch>
Date: Wed, 6 Nov 2024 15:28:55 +0000
Subject: [PATCH] chore: more reductions

---
 .../regression_bignum/src/main.nr             | 45 +++++++------------
 1 file changed, 16 insertions(+), 29 deletions(-)

diff --git a/test_programs/execution_success/regression_bignum/src/main.nr b/test_programs/execution_success/regression_bignum/src/main.nr
index aea1ad3f47d..013ab6b2023 100644
--- a/test_programs/execution_success/regression_bignum/src/main.nr
+++ b/test_programs/execution_success/regression_bignum/src/main.nr
@@ -1,64 +1,51 @@
-pub struct U60Repr<let N: u32, let NumSegments: u32> {
-    limbs: [u64; N * NumSegments],
-}
-
 fn main() {
     let numerator =
         [790096867046896348, 1063071665130103641, 602707730209562162, 996751591622961462, 28650, 0];
-    let denominator = [12, 0, 0, 0, 0, 0];
-
     unsafe { __udiv_mod(numerator) };
 
+    let denominator = [12, 0, 0, 0, 0, 0];
     let result = unsafe { __validate_gt_remainder(denominator) };
     assert(result[4] == 0);
     assert(result[5] == 0);
 }
 
-unconstrained fn __udiv_mod<let N: u32>(remainder_u60: [u64; 2 * N]) {
+unconstrained fn __udiv_mod(remainder_u60: [u64; 6]) {
     let bit_difference = get_msb(remainder_u60);
-    let mut accumulator_u60: U60Repr<N, 2> = U60Repr { limbs: [0; N * 2] };
-    accumulator_u60.limbs[0] = 1;
-    accumulator_u60 = shl(accumulator_u60, bit_difference);
+    let accumulator_u60: [u64; 6] = shl(bit_difference);
 }
 
-unconstrained fn __validate_gt_remainder<let N: u32>(a_u60: [u64; N]) -> [u64; N] {
-    let mut addend_u60: [u64; N] = [0; N];
-    let mut result_u60: [u64; N] = [0; N];
+unconstrained fn __validate_gt_remainder(a_u60: [u64; 6]) -> [u64; 6] {
+    let mut addend_u60: [u64; 6] = [0; 6];
+    let mut result_u60: [u64; 6] = [0; 6];
 
-    for i in 0..N {
+    for i in 0..6 {
         result_u60[i] = a_u60[i] + addend_u60[i];
     }
 
     result_u60
 }
 
-unconstrained fn get_msb<let N: u32>(val: [u64; N]) -> u32 {
+unconstrained fn get_msb(val: [u64; 6]) -> u32 {
     let mut count = 0;
-    for i in 0..N {
-        let v = val[(N - 1) - i];
+    for i in 0..6 {
+        let v = val[(6 - 1) - i];
         if (v > 0) {
-            count = 60 * ((N - 1) - i);
+            count = 60 * ((6 - 1) - i);
             break;
         }
     }
     count
 }
 
-fn shl<let N: u32>(val: U60Repr<N, 2>, shift: u32) -> U60Repr<N, 2> {
-    let mut result: U60Repr<N, 2> = U60Repr { limbs: [0; 2 * N] };
-
+unconstrained fn shl(shift: u32) -> [u64; 6] {
     let num_shifted_limbs = shift / 60;
     let limb_shift = (shift % 60) as u8;
 
-    let mask: u64 = (1 as u64 << 60) - 1;
-    let value = val.limbs[0];
-
-    result.limbs[num_shifted_limbs] = (value << limb_shift) & mask;
+    let mut result = [0; 6];
+    result[num_shifted_limbs] = (1 << limb_shift);
 
-    for i in 1..((N * 2) - num_shifted_limbs) {
-        let value = val.limbs[i];
-        let upshift = (value << limb_shift) & mask;
-        result.limbs[i + num_shifted_limbs] = upshift;
+    for i in 1..(6 - num_shifted_limbs) {
+        result[i + num_shifted_limbs] = 0;
     }
     result
 }