From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sat, 24 Jul 2021 12:06:47 +0000 (+0100)
Subject: add experiment to convert int to float and multiply by PI etc.
X-Git-Tag: xlen-bcd~214
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7073b3e9f127d97c00a06b658cce2b1fd12090cb;p=openpower-isa.git

add experiment to convert int to float and multiply by PI etc.
for later use in DCT
---

diff --git a/src/openpower/decoder/isa/test_caller_transcendentals.py b/src/openpower/decoder/isa/test_caller_transcendentals.py
index a571dace..92788066 100644
--- a/src/openpower/decoder/isa/test_caller_transcendentals.py
+++ b/src/openpower/decoder/isa/test_caller_transcendentals.py
@@ -26,7 +26,7 @@ class FPTranscendentalsTestCase(FHDLTestCase):
         for i in range(32):
             self.assertEqual(sim.fpr(i), SelectableInt(expected_fpr[i], 64))
 
-    def test_fp_sins_coss(self):
+    def tst_fp_sins_coss(self):
         """>>> lst = ["fsins 1, 2",
                       "fcoss 3, 2",
                      ]
@@ -56,6 +56,54 @@ class FPTranscendentalsTestCase(FHDLTestCase):
                     self.assertEqual(sim.fpr(1), SelectableInt(t, 64))
                     self.assertEqual(sim.fpr(3), SelectableInt(u, 64))
 
+    def test_fp_coss_cvt(self):
+        """>>> lst = [
+                      "fcoss 3, 2",
+                     ]
+        """
+        lst = SVP64Asm(["stw 1, 0(0)",
+                        "lfd 0, 0(0)",
+                        "fcfids 0, 0",
+                        "fadds 0, 0, 3", # plus 0.5
+                        "fmuls 0, 0, 1", # times PI
+                        "fdivs 0, 0, 2", # div 4.0
+                        "fcoss 4, 0",
+                     ])
+        lst = list(lst)
+
+        with Program(lst, bigendian=False) as program:
+            gprs = [0] * 32
+            fprs = [0] * 32
+            # constants
+            fprs[3] = fp64toselectable(0.5)     # 0.5
+            fprs[1] = fp64toselectable(math.pi) # pi
+            fprs[2] = fp64toselectable(4.0)     # 4.0
+            #for i in range(-8, 9):
+            for i in range(7, 8):
+                a = math.pi * ((i+0.5) / 4.0)
+                gprs[1] = i
+                a1 = DOUBLE2SINGLE(fp64toselectable(a)) # to Power single
+                a = float(a1)
+                u = math.cos(a)
+                u = DOUBLE2SINGLE(fp64toselectable(u)) # convert to Power single
+
+                with self.subTest():
+                    sim = self.run_tst_program(program, gprs, initial_fprs=fprs)
+                    print("FPR 0", sim.fpr(0), float(sim.fpr(0)))
+                    print("FPR 1", sim.fpr(1), float(sim.fpr(1)))
+                    print("FPR 2", sim.fpr(2), float(sim.fpr(2)))
+                    print("FPR 3", sim.fpr(3), float(sim.fpr(3)))
+                    print("FPR 4", sim.fpr(4), float(sim.fpr(4)))
+                    # sign should not do this, but hey
+                    actual_r = float(sim.fpr(0))
+                    expected_r = float(a1)
+                    err = abs(actual_r - expected_r ) / expected_r
+                    self.assertTrue(err < 1e-6)
+                    actual_r = float(sim.fpr(4))
+                    expected_r = float(u)
+                    err = abs(actual_r - expected_r ) / expected_r
+                    self.assertTrue(err < 1e-6)
+
     def run_tst_program(self, prog, initial_regs=None,
                               initial_mem=None,
                               initial_fprs=None):