From e12e0ee56198eedfb7770783d7153429b5fde3f4 Mon Sep 17 00:00:00 2001
From: Krzosa Karol <krzosa.karol@gmail.com>
Date: Sun, 5 Jun 2022 15:09:40 +0200
Subject: [PATCH] Checking if in range

---
 big_int.cpp | 135 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 123 insertions(+), 12 deletions(-)

diff --git a/big_int.cpp b/big_int.cpp
index 79965b7..7a99e9e 100644
--- a/big_int.cpp
+++ b/big_int.cpp
@@ -30,12 +30,14 @@ We use two's complement
 
 struct S128{
   U64 hi, lo;
-  constexpr S128 max(){return {S64MAX, U64MAX};}
-  constexpr S128 min(){return {(U64)S64MIN, 0};}
-  #define S128MAX S128::max()
-  #define S128MIN S128::min()
 };
 
+function S128
+s128(U64 hi, U64 lo){
+  S128 result = {hi,lo};
+  return result;
+}
+
 function S64
 is_negative(S128 v){
   S64 result = v.hi >> 63;
@@ -94,9 +96,17 @@ operator-(S128 a){
   return a;
 }
 
+/*
+2022.05.06 - Mod and Div
+@hack: only values less then U64MAX -U64MAX
+
+modulo can only overflow in this case (-)S64MIN % -1 || (-)S64MIN % -1 for ints
+casuse the sign flips and MAX is smaller then MIN
+so we do the arithmetic in UINT and convert back
+*/
+
 function S128
 s128_div_hack(S128 a, S128 b){
-  // @hack: only values less then U64MAX -U64MAX
   S64 sign = 1;
   if(is_negative(a)){
     sign *= -1;
@@ -113,6 +123,24 @@ s128_div_hack(S128 a, S128 b){
   return result;
 }
 
+function S128
+s128_mod_hack(S128 a, S128 b){
+  S64 sign = 1;
+  if(is_negative(a)){
+    sign *= -1;
+    a = -a;
+  }
+  if(is_negative(b)){
+    sign *= -1;
+    b = -b;
+  }
+  assert(a.hi == 0 && b.hi == 0);
+  U64 division = a.lo % b.lo;
+  S128 result = {0, division};
+  if(sign == -1) result = -result;
+  return result;
+}
+
 function S128
 u64_mul(U64 u, U64 v){
   U64 u_lo = lo32(u);
@@ -142,6 +170,70 @@ operator==(S128 a, S128 b){
   return result;
 }
 
+function B32
+operator!=(S128 a, S128 b){
+  B32 result = !(a == b);
+  return result;
+}
+
+function B32
+operator<(S128 a, S128 b){
+  if(a.hi != b.hi){
+    S64 a_hi = (S64)a.hi;
+    S64 b_hi = (S64)b.hi;
+    return a_hi < b_hi;
+  }
+
+  return a.lo < b.lo;
+}
+
+function B32
+operator>(S128 a, S128 b){
+  if(a.hi != b.hi){
+    S64 a_hi = (S64)a.hi;
+    S64 b_hi = (S64)b.hi;
+    return a_hi > b_hi;
+  }
+  return a.lo > b.lo;
+}
+
+constexpr S128 const_s128_from_s64(S64 value){return {value < 0 ? ~0 : 0ull, (U64)value};}
+constexpr S128 S128_max(){return {S64MAX, U64MAX};}
+constexpr S128 S128_min(){return {(U64)S64MIN, 0};}
+constexpr S128 S64_max() {return const_s128_from_s64(S64MAX);}
+constexpr S128 S64_min() {return const_s128_from_s64(S64MIN);}
+constexpr S128 S32_max() {return const_s128_from_s64(S32MAX);}
+constexpr S128 S32_min() {return const_s128_from_s64(S32MIN);}
+constexpr S128 S16_max() {return const_s128_from_s64(S16MAX);}
+constexpr S128 S16_min() {return const_s128_from_s64(S16MIN);}
+constexpr S128 S8_max()  {return const_s128_from_s64(S8MAX);}
+constexpr S128 S8_min()  {return const_s128_from_s64(S8MIN);}
+constexpr S128 U64_max() {return {0, U64MAX};}
+constexpr S128 U64_min() {return {};}
+constexpr S128 U32_max() {return {0, U32MAX};}
+constexpr S128 U32_min() {return {};}
+constexpr S128 U16_max() {return {0, U16MAX};}
+constexpr S128 U16_min() {return {};}
+constexpr S128 U8_max()  {return {0, U8MAX};}
+constexpr S128 U8_min()  {return {};}
+
+function B32
+is_out_of_bounds(S128 value, Ast_Resolved_Type *type){
+#define BOUNDS_CASE(T) case TYPE_##T: return (value < T##_min()) || (value > T##_max())
+  switch(type->kind){
+    BOUNDS_CASE(S8);
+    BOUNDS_CASE(S16);
+    BOUNDS_CASE(S32);
+    BOUNDS_CASE(S64);
+    BOUNDS_CASE(U8);
+    BOUNDS_CASE(U16);
+    BOUNDS_CASE(U32);
+    BOUNDS_CASE(U64);
+    invalid_default_case;
+  }
+  return 0;
+}
+
 function void
 test_big_int(){
   S128 v1 = s128_from_s64(-1);
@@ -149,14 +241,14 @@ test_big_int(){
   assert(is_negative(v1));
   assert(sign(v1) == -1);
 
-  S128 v2 = s128_from_u64(U64MAX) + s128_from_u64(1);
+  S128 v2 = U64_max() + s128_from_u64(1);
   assert(v2.lo == 0 && v2.hi == 1);
 
-  S128 v3 = s128_from_u64(U64MAX) + s128_from_u64(100);
+  S128 v3 = U64_max() + s128_from_u64(100);
   assert(v3.lo == 99 && v3.hi == 1);
 
   // S64 s64_max = S64MAX;
-  S128 v4 = s128_from_s64(S64MIN) + s128_from_u64(100);
+  S128 v4 = S64_min() + s128_from_u64(100);
   assert((v4.lo - S64MAX) == 101); // 101 cause S64MIN is larher by 1
 
   S128 v5 = {1, 0};
@@ -193,15 +285,34 @@ test_big_int(){
     assert(!has_value_bigger_then_64bit(v7));
   }
 
-  S128 v8 = s128_div_hack(-s128_from_u64(U64MAX), s128_from_s64(-1));
+  S128 v8 = s128_div_hack(-U64_max(), s128_from_s64(-1));
   assert(v8.lo == U64MAX && v8.hi == 0);
 
-  S128 v9 = s128_div_hack(s128_from_u64(S64MAX), s128_from_s64(S64MAX));
+  S128 v9 = s128_div_hack(S64_max(), S64_max());
   assert(v9 == s128_from_s64(1));
 
-  S128 v10 = s128_div_hack(-s128_from_u64(S64MAX), s128_from_s64(S64MAX));
+  S128 v10 = s128_div_hack(-S64_max(), S64_max());
   assert(v10 == -s128_from_s64(1));
 
-  S128 v11 = s128_div_hack(s128_from_s64(S64MIN), s128_from_s64(S64MAX));
+  S128 v11 = s128_div_hack(S64_min(), S64_max());
   assert(v11 == -s128_from_u64(1));
+
+  {
+    S128 v12 = s128_div_hack(s128_from_s64(-100), s128_from_s64(10));
+    assert(v12 == -s128_from_u64(10));
+  }
+
+  {
+    assert(s128_from_s64(32) > s128_from_s64(16));
+    assert(s128_from_s64(-32) < s128_from_s64(-16));
+    assert(s128_from_s64(S64MIN) < (s128_from_s64(S64MIN)+s128_from_s64(10)));
+    assert(s128_from_s64(S64MIN) > (s128_from_s64(S64MIN)-s128_from_s64(10)));
+    assert(S64_min()*s128_from_u64(4) < S64_min());
+  }
+  {
+    assert(!is_out_of_bounds(S64_max(), type_s64));
+    assert(is_out_of_bounds(s128_from_s64(-19), type_u64));
+    assert(!is_out_of_bounds(s128_from_s64(-19), type_s64));
+    assert(is_out_of_bounds(U64_max(), type_s64));
+  }
 }
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