From bcb51764b8d4a557902a6df5e1c4f39ebe1e6afe Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <kwojtus@protonmail.com>
Date: Thu, 25 Apr 2019 13:47:29 +0200
Subject: enable mul implementation selection on command line, improve error
 notifications for wrong arguments

---
 src/main.F90 | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/src/main.F90 b/src/main.F90
index 97e8e2d..d6b8002 100644
--- a/src/main.F90
+++ b/src/main.F90
@@ -7,12 +7,11 @@ PROGRAM mul
 
   integer, parameter :: seed = 123456
   real :: time
-  integer :: dim = 10, multype = 1, real_kind, stat
-  character(5) :: kind_arg
+  integer :: dim = 10, multype, real_kind, stat
+  character(5) :: kind_arg, impl_arg
 
-  IF (command_argument_count() < 1) THEN
-     write (error_unit, *) "Usage: mul KIND", char(10), &
-                           "where KIND is one of: 4, 8, 16"
+  IF (command_argument_count() < 2) THEN
+     call print_usage()
      STOP
   END IF
 
@@ -21,10 +20,27 @@ PROGRAM mul
   read (kind_arg, *, iostat = stat) real_kind
 
   IF (stat .ne. 0) THEN
-     write (error_unit, *) "Couldn't parse kind number argument"
+     write (error_unit, '(A)') "Couldn't parse kind number argument"
+     call print_usage()
      STOP
   END IF     
-  
+
+  call get_command_argument(2, impl_arg)
+
+  IF      (trim(impl_arg) .eq. "naiv") THEN
+     multype = 1
+  ELSE IF (trim(impl_arg) .eq. "bett") THEN
+     multype = 2
+  ELSE IF (trim(impl_arg) .eq. "dot")  THEN
+     multype = 3
+  ELSE IF (trim(impl_arg) .eq. "mat")  THEN
+     multype = 4
+  ELSE
+     write (error_unit, '(A)') "Unrecognized implementation argument"
+     call print_usage()
+     STOP     
+  END IF
+     
   DO WHILE (dim < 2000)
 
      SELECT CASE(real_kind)
@@ -35,7 +51,8 @@ PROGRAM mul
         CASE (16,3)
            time = measure_16(dim)
         CASE default
-           write (error_unit, *) "wrong kind for real: ", real_kind
+           write (error_unit, '(A,I6)')            &
+                "wrong kind for real:", real_kind
            STOP
 
      END SELECT
@@ -48,6 +65,16 @@ PROGRAM mul
 
 CONTAINS
 
+  SUBROUTINE print_usage()
+    
+    write (*, '(A)')                                             &
+          "Usage: mul KIND IMPLEMENTATION" // char(10) //        &
+          "where KIND is one of: 4, 8, 16" // char(10) //        &
+          "      IMPLEMENTATION is one of: naiv, bett, dot, mat"
+    
+  END SUBROUTINE print_usage
+
+  
   SUBROUTINE init_random_seed()
     integer :: i, n
     
-- 
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