From efc43142a69a81deffbd135719cd5933fda6f1d6 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Thu, 15 Aug 2019 16:42:59 +0800
Subject: [PATCH] wrpll/thls: implement min/max

---
 artiq/gateware/wrpll/thls.py | 46 ++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/artiq/gateware/wrpll/thls.py b/artiq/gateware/wrpll/thls.py
index 0cc244806..f1b9a5947 100644
--- a/artiq/gateware/wrpll/thls.py
+++ b/artiq/gateware/wrpll/thls.py
@@ -47,6 +47,12 @@ class MulShiftIsn(Isn):
 
 # opcode = 4: MulShift with alternate shift
 
+class MinIsn(Isn):
+    opcode = 5
+
+class MaxIsn(Isn):
+    opcode = 6
+
 class CopyIsn(Isn):
     opcode = 7
 
@@ -110,6 +116,22 @@ class ASTCompiler:
             output = self.get_ssa_reg()
             self.program.append(cons(inputs=[left, right], outputs=[output]))
             return output
+        elif isinstance(node, ast.Call):
+            if not isinstance(node.func, ast.Name):
+                raise NotImplementedError
+            funcname = node.func.id
+            if node.keywords:
+                raise NotImplementedError
+            inputs = [self.emit(x) for x in node.args]
+            if funcname == "min":
+                cons = MinIsn
+            elif funcname == "max":
+                cons = MaxIsn
+            else:
+                raise NotImplementedError
+            output = self.get_ssa_reg()
+            self.program.append(cons(inputs=inputs, outputs=[output]))
+            return output
         elif isinstance(node, ast.Num):
             if node.n in self.constants:
                 return self.constants[node.n]
@@ -149,6 +171,8 @@ class Processor:
             AddIsn: 2,
             SubIsn: 2,
             MulShiftIsn: 1 + self.multiplier_stages,
+            MinIsn: 2,
+            MaxIsn: 2,
             CopyIsn: 1,
             InputIsn: 1
         }[isn.__class__]
@@ -364,6 +388,20 @@ class OpUnit(BaseUnit):
         ]
 
 
+class SelectUnit(BaseUnit):
+    def __init__(self, op, data_width):
+        BaseUnit.__init__(self, data_width)
+
+        self.sync += [
+            self.stb_o.eq(self.stb_i),
+            If(op(self.i0, self.i1),
+                self.o.eq(self.i0)
+            ).Else(
+                self.o.eq(self.i1)
+            )
+        ]
+
+
 class CopyUnit(BaseUnit):
     def __init__(self, data_width):
         BaseUnit.__init__(self, data_width)
@@ -468,10 +506,12 @@ class ProcessorImpl(Module):
                 pd.data_width, pd.multiplier_stages)
         else:
             multiplier = NopUnit(pd.data_width)
+        minu = SelectUnit(operator.lt, pd.data_width)
+        maxu = SelectUnit(operator.gt, pd.data_width)
         copier = CopyUnit(pd.data_width)
         inu = InputUnit(pd.data_width, self.input_stb, self.input)
         outu = OutputUnit(pd.data_width, self.output_stb, self.output)
-        units = [nop, adder, subtractor, multiplier, copier, inu, outu]
+        units = [nop, adder, subtractor, multiplier, minu, maxu, copier, inu, outu]
         self.submodules += units
 
         for unit in units:
@@ -490,6 +530,8 @@ class ProcessorImpl(Module):
             (SubIsn.opcode,            subtractor),
             (MulShiftIsn.opcode,       multiplier),
             (MulShiftIsn.opcode + 1,   multiplier),
+            (MinIsn.opcode,            minu),
+            (MaxIsn.opcode,            maxu),
             (CopyIsn.opcode,           copier),
             (InputIsn.opcode,          inu),
             (OutputIsn.opcode,         outu)
@@ -527,7 +569,7 @@ def foo(x):
 
 
 def simple_test(x):
-    return (x*2 >> 1) + 2
+    return min((x*2 >> 1) + 2, 10)
 
 
 if __name__ == "__main__":