From 08c8018bc3a544b57f5cbc310144c6f089e5fedf Mon Sep 17 00:00:00 2001
From: diehoq <diego.polimeni@epfl.ch>
Date: Mon, 10 Jun 2024 15:39:55 +0000
Subject: [PATCH] Implement custom modular adder

---
 .../modular_qft_addition.py                   | 47 ++++++++++++++++++-
 src/qrisp/qtypes/quantum_modulus.py           | 20 ++++----
 2 files changed, 55 insertions(+), 12 deletions(-)

diff --git a/src/qrisp/arithmetic/modular_arithmetic/modular_qft_addition.py b/src/qrisp/arithmetic/modular_arithmetic/modular_qft_addition.py
index 50733688..265da4e2 100644
--- a/src/qrisp/arithmetic/modular_arithmetic/modular_qft_addition.py
+++ b/src/qrisp/arithmetic/modular_arithmetic/modular_qft_addition.py
@@ -23,7 +23,7 @@
 from qrisp.qtypes.quantum_bool import QuantumBool
 from qrisp.arithmetic import multi_controlled_U_g, hybrid_mult, U_g
 from qrisp.core.library import QFT, h, cx, swap
-from qrisp.environments import conjugate, control, invert
+from qrisp.environments import conjugate, control, invert, custom_control
 from qrisp.circuit import Operation
 from qrisp.arithmetic.modular_arithmetic.mod_tools import modinv, montgomery_decoder, montgomery_encoder
 
@@ -49,7 +49,7 @@ def montgomery_addition(a, b):
 def beauregard_adder(a, b, modulus):
     
     if modulus > 2**a.size:
-        raise Exception("Tried to perform modular addition on QuantumFloat with to few qubits")
+        raise Exception("Tried to perform modular addition on QuantumFloat with too few qubits")
     if modulus == 2**a.size:
         with conjugate(QFT)(a, exec_swap = False):
             qft_basis_adder(b, a)
@@ -95,4 +95,47 @@ def beauregard_adder(a, b, modulus):
     sign.delete()
     reduction_not_necessary.delete()
 
+@custom_control
+def mod_adder(a, b, inpl_adder, modulus, ctrl = None):
+    
+    reduction_not_necessary = QuantumBool()
+    sign = QuantumBool()
+    
+    
+    if isinstance(a, int):
+        a = a%modulus
+    
+    b = list(b) + [sign[0]]
+    
+    if ctrl is None:
+        inpl_adder(a, b)
+    else:
+        with control(ctrl):
+            inpl_adder(a, b)
+            
+    with invert():
+        inpl_adder(modulus, b)
 
+    cx(sign, reduction_not_necessary)
+    
+    with control(reduction_not_necessary):
+        inpl_adder(modulus, b)
+        
+    with invert():
+        if ctrl is None:
+            inpl_adder(a, b)
+        else:
+            with control(ctrl):
+                inpl_adder(a, b)
+    
+    cx(sign, reduction_not_necessary)
+    reduction_not_necessary.flip()
+    
+    if ctrl is None:
+        inpl_adder(a, b)
+    else:
+        with control(ctrl):
+            inpl_adder(a, b)
+    
+    sign.delete()
+    reduction_not_necessary.delete()
\ No newline at end of file
diff --git a/src/qrisp/qtypes/quantum_modulus.py b/src/qrisp/qtypes/quantum_modulus.py
index be0684e6..f8a560b5 100644
--- a/src/qrisp/qtypes/quantum_modulus.py
+++ b/src/qrisp/qtypes/quantum_modulus.py
@@ -235,11 +235,11 @@ def __add__(self, other):
                 raise Exception("Tried to add a QuantumFloat and QuantumModulus with non-zero Montgomery shift")
             
         
-        from qrisp.arithmetic.modular_arithmetic import beauregard_adder
+        from qrisp.arithmetic.modular_arithmetic import mod_adder
         
         res = self.duplicate(init = True)
         
-        beauregard_adder(res, other, self.modulus)
+        mod_adder(other, res, self.inpl_adder, self.modulus)
         
         return res
     
@@ -258,9 +258,9 @@ def __iadd__(self, other):
             if self.m != 0:
                 raise Exception("Tried to add a QuantumFloat and QuantumModulus with non-zero Montgomery shift")
             
-        from qrisp.arithmetic.modular_arithmetic import beauregard_adder
+        from qrisp.arithmetic.modular_arithmetic import mod_adder
         
-        beauregard_adder(self, other, self.modulus)
+        mod_adder(other, self, self.inpl_adder, self.modulus)
         return self
 
     @gate_wrap(permeability="args", is_qfree=True)
@@ -275,11 +275,11 @@ def __sub__(self, other):
                 raise Exception("Tried to subtract a QuantumFloat and QuantumModulus with non-zero Montgomery shift")
             
         
-        from qrisp.arithmetic.modular_arithmetic import beauregard_adder
+        from qrisp.arithmetic.modular_arithmetic import mod_adder
         res = self.duplicate(init = True)
         
         with invert():
-            beauregard_adder(res, other, self.modulus)
+            mod_adder(other, res, self.inpl_adder, self.modulus)
         
         return res
 
@@ -294,12 +294,12 @@ def __rsub__(self, other):
             if self.m != 0:
                 raise Exception("Tried to subtract a QuantumFloat and QuantumModulus with non-zero Montgomery shift")
             
-        from qrisp.arithmetic.modular_arithmetic import beauregard_adder
+        from qrisp.arithmetic.modular_arithmetic import mod_adder
         res = self.duplicate()
         
         res -= self
         
-        beauregard_adder(res, other, self.modulus)
+        mod_adder(other, res, self.inpl_adder, self.modulus)
         
         return res
 
@@ -314,9 +314,9 @@ def __isub__(self, other):
             if self.m != 0:
                 raise Exception("Tried to subtract a QuantumFloat and QuantumModulus with non-zero Montgomery shift")
         
-        from qrisp.arithmetic.modular_arithmetic import beauregard_adder
+        from qrisp.arithmetic.modular_arithmetic import mod_adder
         with invert():
-            beauregard_adder(self, other, self.modulus)
+            mod_adder(other, self, self.inpl_adder, self.modulus)
         
         return self