arbitrary stack size at runtime

Author: scivision

README.md

@@ -10,9 +10,9 @@ Specifically, RPNcalc has been tested on Linux, Mac and Windows, including:
 * Gfortran 6, 7, 8 
 * ifort 2019
 
-However, due to lack of basic Fortran 2008 support, the following compilers do NOT yet work:
-* Flang 5.0
-* PGI 2018
+The stack size is set by the user with command line option. 
+Default size is 4.
+
 
 #### Authors
 * Fortran 77 code: David G. Simpson
@@ -43,7 +43,13 @@ For example:
 To exit the program, type: 
 
     q
-    
+
+### set stack size
+The default stack size is 4.
+Set the stack size at runtime, say 25 by:
+
+    rpncalc 25
+
 
 Show what modes the calculator is in with:
 
@@ -391,3 +397,9 @@ Many functions not commonly found in RPN calculators are included:
     ?           Exponential integrals
     ?           Hypergeometric functions
     ?           Hermite polynomials
+    
+## Notes
+
+Due to lack of basic Fortran 2008 support, the following compilers do NOT yet work:
+* Flang 5.0
+* PGI 2018

src/calc.f90

@@ -38,7 +38,8 @@ PROGRAM RPN
 
 !
 !     Initialize data.
-!
+
+      call init_stack()
 
       DEL = IACHAR('a') - IACHAR('A')                                               ! find ASCII position diff between 'A' and 'a'
 

src/reg.f90

@@ -3,15 +3,15 @@ MODULE GLOBAL
 
 IMPLICIT NONE
 
-CHARACTER(*), PARAMETER :: VERSION = '1.1.3'
+CHARACTER(*), PARAMETER :: VERSION = '1.1.4'
 
-INTEGER, PARAMETER :: STACK_SIZE = 4                                          ! stack size
+INTEGER :: STACK_SIZE                                         ! stack size
 INTEGER, PARAMETER :: REG_SIZE = 10                                           ! number of storage registers
-real(wp), DIMENSION (STACK_SIZE) :: STACK                             ! real stack
+real(wp), allocatable :: STACK(:)                           ! real stack
 real(wp), DIMENSION (0:REG_SIZE-1) :: REG                             ! real storage registers
-COMPLEX(wp), DIMENSION (STACK_SIZE) :: CSTACK                             ! complex stack
+COMPLEX(wp), allocatable :: CSTACK(:)                           ! complex stack
 COMPLEX(wp), DIMENSION (0:REG_SIZE-1) :: CREG                             ! complex storage registers
-INTEGER, DIMENSION (STACK_SIZE) :: RNSTACK, RDSTACK                           ! rational stack
+INTEGER, allocatable :: RNSTACK(:), RDSTACK(:)                      ! rational stack
 INTEGER, DIMENSION (0:REG_SIZE-1) :: RNREG, RDREG                             ! rational storage registers
 real(wp) :: LASTX                                                     ! real LAST X register
 COMPLEX(wp) :: CLASTX                                                     ! complex LAST X register
@@ -32,4 +32,21 @@ MODULE GLOBAL
 INTEGER, PARAMETER :: INITIAL_FRACTION_MODE = 1                               ! 1=improper, 2=mixed
 real(wp), PARAMETER :: INITIAL_FRACTOL = 1.0D-4                       ! tolerance for decimal to fraction conversion
 
+
+contains
+
+
+subroutine init_stack()
+
+integer :: i
+character(16) :: argv
+
+stack_size=4  ! default
+call get_command_argument(1, argv, status=i)
+if (i==0) read(argv,'(I2)') stack_size
+
+allocate(stack(stack_size), cstack(stack_size), rdstack(stack_size), rnstack(stack_size))
+
+end subroutine init_stack
+
 END MODULE GLOBAL