Make the API not suck.

Seriously, not sure what I was thinking with the attributes type.

10 files changed, 94 insertions, 183 deletions

diff --git a/src/sandglass.c b/src/sandglass.c
index 6a492c3..7ffe511 100644
--- a/src/sandglass.c
+++ b/src/sandglass.c
@@ -24,130 +24,61 @@
 #include <time.h>
 #include <errno.h>
 
-static int sandglass_real_create(sandglass_t *sandglass,
-                                 const sandglass_attributes_t *attr);
-
-/* Create a timer */
 int
-sandglass_create(sandglass_t *sandglass,
-                 const sandglass_attributes_t *min,
-                 const sandglass_attributes_t *max)
+sandglass_init_introspective(sandglass_t *sandglass, sandglass_resolution_t res)
 {
-  sandglass_attributes_t realmin, realmax;
-
-  /* Get our real min and max values */
-
-  if (min)
-    realmin = *min;
-  else {
-    /* min defaults to { SANDGLASS_INTROSPECTIVE, SANDGLASS_SYSTEM } */
-    realmin.incrementation = SANDGLASS_INTROSPECTIVE;
-    realmin.resolution     = SANDGLASS_SYSTEM;
-  }
-
-  if (max)
-    realmax = *max;
-  else {
-    /* max defaults to the greater of min and { SANDGLASS_INTROSPECTIVE,
-       SANDGLASS_CPUTIME } */
-    if (realmin.incrementation > SANDGLASS_INTROSPECTIVE
-        || (realmin.incrementation == SANDGLASS_INTROSPECTIVE
-            && realmin.resolution > SANDGLASS_CPUTIME))
-      realmax = realmin;
-    else {
-      realmax.incrementation = SANDGLASS_INTROSPECTIVE;
-      realmax.resolution     = SANDGLASS_CPUTIME;
-    }
-  }
-
-  /* Ensure max >= min */
-  if (realmax.incrementation < realmin.incrementation
-      || (realmax.incrementation == realmin.incrementation
-          && realmax.resolution < realmin.resolution))
-  {
-    errno = EINVAL;
-    return -1;
-  }
-
-  /* Now search for available timers, starting from max */
-
-  while (sandglass_real_create(sandglass, &realmax) != 0) {
-    /* Once we reach the minimum attributes, bail out */
-    if (realmax.incrementation == realmin.incrementation
-        && realmax.resolution == realmin.resolution)
-    {
+  switch (res) {
+  case SANDGLASS_CPUTIME:
+    if (sysconf(_SC_THREAD_CPUTIME) > 0 || sysconf(_SC_CPUTIME) > 0) {
+      sandglass->freq  = 1e9;
+      sandglass->loops = 1;
+    } else {
       errno = ENOTSUP;
       return -1;
     }
+    break;
 
-    /* Try the next lowest allowable settings */
-    if (realmax.resolution)
-      --realmax.resolution;
-    else {
-      if (realmax.incrementation) {
-        --realmax.incrementation;
-        realmax.resolution = SANDGLASS_CPUTIME;
-      } else {
-        errno = ENOTSUP;
-        return -1;
-      }
-    }
+  case SANDGLASS_SYSTEM:
+    sandglass->freq  = CLOCKS_PER_SEC;
+    sandglass->loops = 1;
+    break;
+
+  default:
+    errno = EINVAL;
+    return -1;
   }
 
+  sandglass->incrementation = SANDGLASS_INTROSPECTIVE;
+  sandglass->resolution     = res;
   return 0;
 }
 
-static int
-sandglass_real_create(sandglass_t *sandglass,
-                      const sandglass_attributes_t *attr)
+int
+sandglass_init_monotonic(sandglass_t *sandglass, sandglass_resolution_t res)
 {
-  switch (attr->incrementation) {
-    case SANDGLASS_MONOTONIC:
-      switch (attr->resolution) {
-        case SANDGLASS_CPUTIME:
+  switch (res) {
+  case SANDGLASS_CPUTIME:
 #ifdef SANDGLASS_TSC
-          sandglass->resolution = sandglass_tsc_resolution();
-          sandglass->loops      = sandglass_tsc_loops();
-          break;
+    sandglass->freq  = sandglass_tsc_freq();
+    sandglass->loops = sandglass_tsc_loops();
+    break;
 #else
-          return -1;
+    errno = ENOTSUP;
+    return -1;
 #endif
 
-        case SANDGLASS_SYSTEM:
-          sandglass->resolution = 1e9;
-          sandglass->loops      = 1;
-          break;
+  case SANDGLASS_SYSTEM:
+    sandglass->freq  = 1e9;
+    sandglass->loops = 1;
+    break;
 
-        default:
-          return -1;
-      }
-      break;
-
-    case SANDGLASS_INTROSPECTIVE:
-      switch (attr->resolution) {
-        case SANDGLASS_CPUTIME:
-          if (sysconf(_SC_THREAD_CPUTIME) > 0 || sysconf(_SC_CPUTIME) > 0) {
-            sandglass->resolution = 1e9;
-            sandglass->loops      = 1;
-          } else
-            return -1;
-          break;
-
-        case SANDGLASS_SYSTEM:
-          sandglass->resolution = CLOCKS_PER_SEC;
-          sandglass->loops      = 1;
-          break;
-
-        default:
-          return -1;
-      }
-      break;
-
-    default:
-      return -1;
+  default:
+    errno = EINVAL;
+    return -1;
   }
 
-  sandglass->attributes = *attr;
+  sandglass->incrementation = SANDGLASS_MONOTONIC;
+  sandglass->resolution     = res;
   return 0;
 }
 
@@ -167,7 +98,7 @@ sandglass_elapse(sandglass_t *sandglass)
 {
   long oldgrains = sandglass->grains;
 
-  if (sandglass_real_gettime(sandglass) != 0)
+  if (sandglass_real_gettime(sandglass))
     return -1;
 
   sandglass->grains -= oldgrains;
@@ -185,14 +116,15 @@ sandglass_real_gettime(sandglass_t *sandglass)
   struct timespec ts;
   clock_t clock_ticks;
 
-  switch (sandglass->attributes.incrementation) {
+  switch (sandglass->incrementation) {
     case SANDGLASS_MONOTONIC:
-      switch (sandglass->attributes.resolution) {
+      switch (sandglass->resolution) {
         case SANDGLASS_CPUTIME:
 #ifdef SANDGLASS_TSC
           sandglass->grains = sandglass_get_tsc();
           break;
 #else
+          errno = ENOTSUP;
           return -1;
 #endif
 
@@ -209,12 +141,13 @@ sandglass_real_gettime(sandglass_t *sandglass)
           break;
 
         default:
+          errno = EINVAL;
           return -1;
       }
       break;
 
     case SANDGLASS_INTROSPECTIVE:
-      switch (sandglass->attributes.resolution) {
+      switch (sandglass->resolution) {
         case SANDGLASS_CPUTIME:
           if (sysconf(_SC_THREAD_CPUTIME) > 0) {
             if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts) != 0)
@@ -222,8 +155,10 @@ sandglass_real_gettime(sandglass_t *sandglass)
           } else if (sysconf(_SC_CPUTIME) > 0) {
             if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) != 0)
               return -1;
-          } else
+          } else {
+            errno = EINVAL;
             return -1;
+          }
           sandglass->grains     = ts.tv_nsec;
           sandglass->adjustment = 1000000000L;
           break;
@@ -231,15 +166,17 @@ sandglass_real_gettime(sandglass_t *sandglass)
         case SANDGLASS_SYSTEM:
           if ((clock_ticks = clock()) == -1)
             return -1;
-          sandglass->grains = clock();
+          sandglass->grains = clock_ticks;
           break;
 
         default:
+          errno = EINVAL;
           return -1;
       }
       break;
 
     default:
+      errno = EINVAL;
       return -1;
   }
 
diff --git a/src/sandglass.h b/src/sandglass.h
index 7b7577b..5456391 100644
--- a/src/sandglass.h
+++ b/src/sandglass.h
@@ -31,8 +31,24 @@
 extern "C" {
 #endif
 
-/* A type to represent a clock's time measurement attributes */
-enum sandglass_incrementation_t
+/* A type to represent a clock's timing resolution */
+typedef enum sandglass_resolution_t
+{
+  /*
+   * Rely on the kernel to provide time information; less precise, more
+   * portable
+   */
+  SANDGLASS_SYSTEM,
+
+  /*
+   * Get timing information directly from the processor; more precise, less
+   * portable
+   */
+  SANDGLASS_CPUTIME
+} sandglass_resolution_t;
+
+/* An internal type to represent a clock's time measurement attributes */
+typedef enum sandglass_incrementation_t
 {
   /*
    * A clock which only increments during the current process's execution.  Less
@@ -48,45 +64,20 @@ enum sandglass_incrementation_t
    * while being timed.
    */
   SANDGLASS_MONOTONIC
-};
-typedef enum sandglass_incrementation_t sandglass_incrementation_t;
-
-/* A type to represent a clock's timing resolution */
-enum sandglass_resolution_t
-{
-  /*
-   * Rely on the kernel to provide time information; less precise, more
-   * portable.  Uses times().
-   */
-  SANDGLASS_SYSTEM,
+} sandglass_incrementation_t;
 
-  /*
-   * Get timing information directly from the processor; more precise, less
-   * portable.  Uses the CLOCK_THREAD_CPUTIME_ID clock for
-   * SANDGLASS_INTROSPECTIVE mode, and the raw TSC for SANDGLASS_MONOTONIC.
-   */
-  SANDGLASS_CPUTIME
-};
-typedef enum sandglass_resolution_t sandglass_resolution_t;
-
-/* Attributes of a clock */
-struct sandglass_attributes_t
+/* An high resolution timer */
+typedef struct sandglass_t
 {
+  /* The attributes of the clock */
   sandglass_incrementation_t incrementation;
   sandglass_resolution_t     resolution;
-};
-typedef struct sandglass_attributes_t sandglass_attributes_t;
-
-struct sandglass_t
-{
-  /* The attributes of the clock */
-  sandglass_attributes_t attributes;
 
   /* Units of time which have passed */
   long grains;
 
-  /* grains/resolution should give elapsed time in seconds */
-  double resolution;
+  /* grains/freq should give elapsed time in seconds */
+  double freq;
 
   /*
    * Internal fields
@@ -101,24 +92,13 @@ struct sandglass_t
   /* A field used by sandglass_bench() to store the overhead of
      sandglass_begin()/_elapse(), and of looping */
   long baseline;
-};
-typedef struct sandglass_t sandglass_t;
+} sandglass_t;
 
-/*
- * Creates a timer with at least the precision of `min', and at most the
- * precision of `max'.  Precisions are compared first by incrementation type:
- * all monotonic timers are considered more precise than introspective timers.
- * Then, higher resolution timers take precidence.
- *
- * If `min' is NULL, it defaults to { SANDGLASS_INTROSPECTIVE,
- * SANDGLASS_SYSTEM }.
- *
- * If `max' is NULL, it defaults to at least `min', but not less than
- * { SANDGLASS_INTROSPECTIVE, SANDGLASS_CPUTIME }.
- */
-int sandglass_create(sandglass_t *sandglass,
-                     const sandglass_attributes_t *min,
-                     const sandglass_attributes_t *max);
+/* Create a timer */
+int sandglass_init_introspective(sandglass_t *sandglass,
+                                 sandglass_resolution_t res);
+int sandglass_init_monotonic(sandglass_t *sandglass,
+                             sandglass_resolution_t res);
 
 int sandglass_begin(sandglass_t *sandglass);
 int sandglass_elapse(sandglass_t *sandglass);
diff --git a/src/sandglass_impl.h b/src/sandglass_impl.h
index 689c6bf..accb332 100644
--- a/src/sandglass_impl.h
+++ b/src/sandglass_impl.h
@@ -31,9 +31,9 @@
 #ifdef SANDGLASS_TSC
 /* Read the time stamp counter */
 long sandglass_get_tsc();
-/* Get the timing resolution of the TSC */
-double sandglass_tsc_resolution();
-/* Get the necessary number of loops for SANDGLASS_REALTICKS */
+/* Get the frequency of the TSC */
+double sandglass_tsc_freq();
+/* Get the necessary number of loops for sandglass_bench_fine() */
 unsigned int sandglass_tsc_loops();
 #endif
 
@@ -43,4 +43,4 @@ void sandglass_timespec_sub(struct timespec *ts, const struct timespec *d);
 int  sandglass_timespec_cmp(const struct timespec *a, const struct timespec *b);
 void sandglass_spin(const struct timespec *ts);
 
-#endif /* SANDGLASS_IMPL_H_INCLUDED */
\ No newline at end of file
+#endif /* SANDGLASS_IMPL_H_INCLUDED */
diff --git a/src/tsc.c b/src/tsc.c
index 135cd2a..713008c 100644
--- a/src/tsc.c
+++ b/src/tsc.c
@@ -25,7 +25,7 @@
 
 /* Gets the number of clock ticks per second */
 double
-sandglass_tsc_resolution()
+sandglass_tsc_freq()
 {
   static long tsc = 0;
   static struct timespec ts = { .tv_sec = 0, .tv_nsec = 10000000L };
diff --git a/tests/introspective-cputime.c b/tests/introspective-cputime.c
index 7ce9a36..3f4158e 100644
--- a/tests/introspective-cputime.c
+++ b/tests/introspective-cputime.c
@@ -29,17 +29,16 @@ int
 main()
 {
   sandglass_t sandglass;
-  sandglass_attributes_t attr = { SANDGLASS_INTROSPECTIVE, SANDGLASS_CPUTIME };
   struct timespec tosleep = { .tv_sec = 0, .tv_nsec = 111111111L };
 
-  if (sandglass_create(&sandglass, &attr, &attr) != 0) {
+  if (sandglass_init_introspective(&sandglass, SANDGLASS_CPUTIME) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
 
   sandglass_bench(&sandglass, sandglass_spin(&tosleep));
 
-  printf("%.15g\n", sandglass.grains/sandglass.resolution);
+  printf("%.15g\n", sandglass.grains/sandglass.freq);
 
   return EXIT_SUCCESS;
 }
diff --git a/tests/introspective-system.c b/tests/introspective-system.c
index 81e3397..5dee23a 100644
--- a/tests/introspective-system.c
+++ b/tests/introspective-system.c
@@ -29,17 +29,16 @@ int
 main()
 {
   sandglass_t sandglass;
-  sandglass_attributes_t attr = { SANDGLASS_INTROSPECTIVE, SANDGLASS_SYSTEM };
   struct timespec tosleep = { .tv_sec = 0, .tv_nsec = 111111111L };
 
-  if (sandglass_create(&sandglass, &attr, &attr) != 0) {
+  if (sandglass_init_introspective(&sandglass, SANDGLASS_SYSTEM) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
 
   sandglass_bench(&sandglass, sandglass_spin(&tosleep));
 
-  printf("%.15g\n", sandglass.grains/sandglass.resolution);
+  printf("%.15g\n", sandglass.grains/sandglass.freq);
 
   return EXIT_SUCCESS;
 }
diff --git a/tests/monotonic-cputime.c b/tests/monotonic-cputime.c
index d0a7de1..f034df3 100644
--- a/tests/monotonic-cputime.c
+++ b/tests/monotonic-cputime.c
@@ -29,17 +29,16 @@ int
 main()
 {
   sandglass_t sandglass;
-  sandglass_attributes_t attr = { SANDGLASS_MONOTONIC, SANDGLASS_CPUTIME };
   struct timespec tosleep = { .tv_sec = 0, .tv_nsec = 111111111L };
 
-  if (sandglass_create(&sandglass, &attr, &attr) != 0) {
+  if (sandglass_init_monotonic(&sandglass, SANDGLASS_CPUTIME) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
 
   sandglass_bench(&sandglass, sandglass_spin(&tosleep));
 
-  printf("%.15g\n", sandglass.grains/sandglass.resolution);
+  printf("%.15g\n", sandglass.grains/sandglass.freq);
 
   return EXIT_SUCCESS;
 }
diff --git a/tests/monotonic-realticks.c b/tests/monotonic-realticks.c
index 51404f5..5fff86e 100644
--- a/tests/monotonic-realticks.c
+++ b/tests/monotonic-realticks.c
@@ -30,9 +30,8 @@ int
 main()
 {
   sandglass_t sandglass;
-  sandglass_attributes_t attr = { SANDGLASS_MONOTONIC, SANDGLASS_CPUTIME };
 
-  if (sandglass_create(&sandglass, &attr, &attr) != 0) {
+  if (sandglass_init_monotonic(&sandglass, SANDGLASS_CPUTIME) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
diff --git a/tests/monotonic-system.c b/tests/monotonic-system.c
index 0774908..d8ffba9 100644
--- a/tests/monotonic-system.c
+++ b/tests/monotonic-system.c
@@ -29,17 +29,16 @@ int
 main()
 {
   sandglass_t sandglass;
-  sandglass_attributes_t attr = { SANDGLASS_MONOTONIC, SANDGLASS_SYSTEM };
   struct timespec tosleep = { .tv_sec = 0, .tv_nsec = 111111111L };
 
-  if (sandglass_create(&sandglass, &attr, &attr) != 0) {
+  if (sandglass_init_monotonic(&sandglass, SANDGLASS_SYSTEM) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
 
   sandglass_bench(&sandglass, sandglass_spin(&tosleep));
 
-  printf("%.15g\n", sandglass.grains/sandglass.resolution);
+  printf("%.15g\n", sandglass.grains/sandglass.freq);
 
   return EXIT_SUCCESS;
 }
diff --git a/tests/noprecache.c b/tests/noprecache.c
index 071920d..e48929d 100644
--- a/tests/noprecache.c
+++ b/tests/noprecache.c
@@ -31,10 +31,9 @@ main()
 {
   int i = 0;
   sandglass_t sandglass;
-  sandglass_attributes_t attr = { SANDGLASS_MONOTONIC, SANDGLASS_CPUTIME };
   struct timespec tosleep = { .tv_sec = 0, .tv_nsec = 111111111L };
 
-  if (sandglass_create(&sandglass, &attr, &attr) != 0) {
+  if (sandglass_init_monotonic(&sandglass, SANDGLASS_SYSTEM) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
@@ -49,7 +48,7 @@ main()
             "sandglass_bench_noprecache() evaluated routine %d times!\n", i);
   }
 
-  printf("%.15g\n", sandglass.grains/sandglass.resolution);
+  printf("%.15g\n", sandglass.grains/sandglass.freq);
 
   return EXIT_SUCCESS;
 }