qmckl/src/qmckl_context.org

# -*- mode: org -*-
# vim: syntax=c
#+TITLE: Context

This file is written in C because it is more natural to express the context in
C than in Fortran.

3 files are produced:
- a header file : =qmckl_context.h= 
- a source file : =qmckl_context.c= 
- a test   file : =test_qmckl_context.c= 

*** Header 
    #+BEGIN_SRC C :tangle qmckl_context.h
#ifndef QMCKL_CONTEXT_H
#define QMCKL_CONTEXT_H
#include "qmckl.h"
    #+END_SRC

*** Source
    #+BEGIN_SRC C :tangle qmckl_context.c
#include "qmckl.h"
    #+END_SRC

*** Test
    #+BEGIN_SRC C :tangle test_qmckl_context.c
#include "qmckl.h"                                                                            
#include "munit.h"                                                                            
static MunitResult test_qmckl_context() {  
    #+END_SRC

* Context

  The context variable is a handle for the state of the library, and
  is stored in the following data structure, which can't be seen
  outside of the library. To simplify compatibility with other
  languages, the pointer to the internal data structure is converted
  into a 64-bit signed integer, defined in the =qmckl_context= type.
  A value of 0 for the context is equivalent to a NULL pointer.

*** Header
    #+BEGIN_SRC C :tangle qmckl_context.h
/* 64-bit integer */
typedef long long int qmckl_context ;
    #+END_SRC

*** Source
    #+BEGIN_SRC C :tangle qmckl_context.c
typedef struct qmckl_context_struct {
  struct qmckl_context_struct * prev;
  unsigned int tag;
  int precision;
  int range;
} qmckl_context_struct;

#define VALID_TAG   0xBEEFFACE
#define INVALID_TAG 0xDEADBEEF
    #+END_SRC
    
  The tag is used internally to check if the memory domain pointed by
  a pointer is a valid context.

*** Test
    We declare here the variables used in the tests.
    #+BEGIN_SRC C :tangle test_qmckl_context.c
  qmckl_context  context;
  qmckl_context  new_context;
    #+END_SRC

    
** =qmckl_context_check=
   
   Checks if the domain pointed by the pointer is a valid context.
   Returns the input =qmckl_context= if the context is valid, 0 otherwise.

*** Header
    #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_context qmckl_context_check(qmckl_context context) ;
    #+END_SRC
  
*** Source
    #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_context qmckl_context_check(qmckl_context context) {
  qmckl_context_struct * ctx;

  if (context == (qmckl_context) 0) return (qmckl_context) 0;

  ctx = (qmckl_context_struct*) context;
  if (ctx->tag != VALID_TAG) return (qmckl_context) 0;

  return context; 
}
    #+END_SRC
  
** =qmckl_context_create=

   To create a new context, use =qmckl_context_create()=.
   - On success, returns a pointer to a context using the =qmckl_context= type
   - Returns 0 upon failure to allocate the internal data structure

*** Header
    #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_context qmckl_context_create();
    #+END_SRC

*** Source
    #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_context qmckl_context_create() {

  qmckl_context_struct*  context;

  context = (qmckl_context_struct*) qmckl_malloc (sizeof(qmckl_context_struct));
  if (context == NULL) {
    return (qmckl_context) 0;
  }

  context->prev      = NULL;
  context->precision = QMCKL_DEFAULT_PRECISION;
  context->range     = QMCKL_DEFAULT_RANGE;
  context->tag       = VALID_TAG;

  return (qmckl_context) context;
}
    #+END_SRC
    
*** Test
    #+BEGIN_SRC C :tangle test_qmckl_context.c
  context = qmckl_context_create();
  munit_assert_long( context, !=, (qmckl_context) 0);
  munit_assert_long( qmckl_context_check(context), ==,  context);
    #+END_SRC

** =qmckl_context_copy=

   This function makes a shallow copy of the current context.
   - Copying the 0-valued context returns 0
   - On success, returns a pointer to the new context using the =qmckl_context= type
   - Returns 0 upon failure to allocate the internal data structure
     for the new context

*** Header
   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_context qmckl_context_copy(const qmckl_context context);
   #+END_SRC

*** Source
   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_context qmckl_context_copy(const qmckl_context context) {

  qmckl_context_struct* old_context;
  qmckl_context_struct* new_context;
  qmckl_context checked_context;

  checked_context = qmckl_context_check(context);

  if (checked_context == (qmckl_context) 0) {
    return (qmckl_context) 0;
  }

  new_context = (qmckl_context_struct*) qmckl_malloc (sizeof(qmckl_context_struct));
  if (new_context == NULL) {
    return (qmckl_context) 0;
  }

  old_context = (qmckl_context_struct*) checked_context;

  new_context->prev      = old_context;
  new_context->precision = old_context->precision;
  new_context->range     = old_context->range;
  new_context->tag       = VALID_TAG;

  return (qmckl_context) new_context;
}

   #+END_SRC

*** Test
    #+BEGIN_SRC C :tangle test_qmckl_context.c
  new_context = qmckl_context_copy(context);
  munit_assert_long(new_context, !=, (qmckl_context) 0);
  munit_assert_long(new_context, !=, context);
  munit_assert_long(qmckl_context_check(new_context), ==, new_context);
    #+END_SRC

** =qmckl_context_previous=
   
   Returns the previous context
   - On success, returns the ancestor of the current context
   - Returns 0 for the initial context
   - Returns 0 for the 0-valued context

*** Header
   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_context qmckl_context_previous(const qmckl_context context);
   #+END_SRC

*** Source
   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_context qmckl_context_previous(const qmckl_context context) {

  qmckl_context checked_context;
  qmckl_context_struct* ctx;

  checked_context = qmckl_context_check(context);
  if (checked_context == (qmckl_context) 0) {
    return (qmckl_context) 0;
  }

  ctx = (qmckl_context_struct*) checked_context;
  return qmckl_context_check((qmckl_context) ctx->prev);
}
   #+END_SRC

*** Test
    #+BEGIN_SRC C :tangle test_qmckl_context.c
  munit_assert_long(qmckl_context_previous(new_context), !=, (qmckl_context) 0);
  munit_assert_long(qmckl_context_previous(new_context), ==, context);
  munit_assert_long(qmckl_context_previous(context), ==, (qmckl_context) 0);
  munit_assert_long(qmckl_context_previous((qmckl_context) 0), ==, (qmckl_context) 0);
    #+END_SRC

** =qmckl_context_destroy=
   
   Destroys the current context, leaving the ancestors untouched.
   - Succeeds if the current context is properly destroyed
   - Fails otherwise
   - Fails if the 0-valued context is given in argument
   - Fails if the the pointer is not a valid context
     
*** Header
   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_exit_code qmckl_context_destroy(qmckl_context context);
   #+END_SRC

*** Source
   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_exit_code qmckl_context_destroy(qmckl_context context) {

  qmckl_context_struct* ctx;
  qmckl_context checked_context;
  
  checked_context = qmckl_context_check(context);
  if (checked_context == (qmckl_context) 0) return QMCKL_FAILURE;

  ctx = (qmckl_context_struct*) context;
  if (ctx == NULL) return QMCKL_FAILURE;

  ctx->tag = INVALID_TAG;
  qmckl_free(ctx);
  return QMCKL_SUCCESS;
}
   #+END_SRC

*** Test
    #+BEGIN_SRC C :tangle test_qmckl_context.c
  munit_assert_long(qmckl_context_check(new_context), ==, new_context);
  munit_assert_long(new_context, !=, (qmckl_context) 0);
  munit_assert_int(qmckl_context_destroy(new_context), ==, QMCKL_SUCCESS);
  munit_assert_long(qmckl_context_check(new_context), !=, new_context);
  munit_assert_long(qmckl_context_check(new_context), ==, (qmckl_context) 0);
  munit_assert_long(qmckl_context_destroy((qmckl_context) 0), ==, QMCKL_FAILURE);
    #+END_SRC

    
* Precision

  The following functions set and get the expected required precision
  and range. =precision= should be an integer between 2 and 53, and
 =range= should be an integer between 2 and 11.

  The setter functions functions return a new context as a 64-bit integer.
  The getter functions return the value, as a 32-bit integer.
  The update functions return =QMCKL_SUCCESS= or =QMCKL_FAILURE=.

** =qmckl_context_update_precision=

   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_exit_code qmckl_context_update_precision(const qmckl_context context, int precision);
   #+END_SRC

   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_exit_code qmckl_context_update_precision(const qmckl_context context, int precision) {
  qmckl_context_struct* ctx;

  if (precision <  2) return QMCKL_FAILURE;
  if (precision > 53) return QMCKL_FAILURE;

  ctx = (qmckl_context_struct*) context;
  if (ctx == NULL) return QMCKL_FAILURE;

  ctx->precision = precision;
  return QMCKL_SUCCESS;
}
   #+END_SRC

** =qmckl_context_update_range=
   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_exit_code qmckl_context_update_range(const qmckl_context context, int range);
   #+END_SRC
   
   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_exit_code qmckl_context_update_range(const qmckl_context context, int range) {
  qmckl_context_struct* ctx;

  if (range <  2) return QMCKL_FAILURE;
  if (range > 11) return QMCKL_FAILURE;

  ctx = (qmckl_context_struct*) context;
  if (ctx == NULL) return QMCKL_FAILURE;

  ctx->range = range;
  return QMCKL_SUCCESS;
}
   #+END_SRC



** =qmckl_context_set_precision=

   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_context qmckl_context_set_precision(const qmckl_context context, int precision);
   #+END_SRC

   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_context qmckl_context_set_precision(const qmckl_context context, const int precision) {
  qmckl_context new_context;

  new_context = qmckl_context_copy(context);
  if (new_context == 0) return 0;

  if (qmckl_context_update_precision(context, precision) == QMCKL_FAILURE) return 0;

  return new_context;
}
   #+END_SRC

** =qmckl_context_set_range=
   #+BEGIN_SRC C :tangle qmckl_context.h
qmckl_context qmckl_context_set_range(const qmckl_context context, int range);
   #+END_SRC

   #+BEGIN_SRC C :tangle qmckl_context.c
qmckl_context qmckl_context_set_range(const qmckl_context context, int range) {
  qmckl_context new_context;

  new_context = qmckl_context_copy(context);
  if (new_context == 0) return 0;

  if (qmckl_context_update_range(context, range) == QMCKL_FAILURE) return 0;

  return new_context;
}
   #+END_SRC



** =qmckl_context_get_precision=

   #+BEGIN_SRC C :tangle qmckl_context.h
int qmckl_context_get_precision(const qmckl_context context);
   #+END_SRC

   #+BEGIN_SRC C :tangle qmckl_context.c
int qmckl_context_get_precision(const qmckl_context context) {
  qmckl_context_struct* ctx;
  ctx = (qmckl_context_struct*) context;
  return ctx->precision;
}
   #+END_SRC

** =qmckl_context_get_range=

   #+BEGIN_SRC C :tangle qmckl_context.h
int qmckl_context_get_range(const qmckl_context context);
   #+END_SRC

   #+BEGIN_SRC C :tangle qmckl_context.c
int qmckl_context_get_range(const qmckl_context context) {
  qmckl_context_struct* ctx;
  ctx = (qmckl_context_struct*) context;
  return ctx->range;
}
   #+END_SRC

   

* End of files

*** Header
  #+BEGIN_SRC C :tangle qmckl_context.h
#endif
  #+END_SRC

*** Test
  #+BEGIN_SRC C :tangle test_qmckl_context.c
  return MUNIT_OK;                                                                            
}                                                                                             
                                                                                              
int main(int argc, char* argv[MUNIT_ARRAY_PARAM(argc + 1)]) {                                 
  static MunitTest test_suite_tests[] =                                                       
    {                                                                                         
     { (char*) "qmckl_context", test_qmckl_context, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
     { NULL, NULL, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL }                                 
    };                                                                                        
                                                                                              
    static const MunitSuite test_suite =                                                      
    {                                                                                         
     (char*) "", test_suite_tests, NULL, 1, MUNIT_SUITE_OPTION_NONE                           
    };                                                                                        
                                                                                              
    return munit_suite_main(&test_suite, (void*) "µnit", argc, argv);                         
}        
  #+END_SRC