atrri

commit e3bc6e2ef2f366f044aa0882f3c4ce78a9b1a043
parent 16e27c21f6711060abed6661e21fd404522d4985
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Wed, 13 Jan 2021 12:53:44 +0100

Implement the atrri_fetch_refractive_index function

Diffstat:
M
src/atrri.c
 | 
79
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
src/atrri.h
 | 
7
++++++-

2 files changed, 85 insertions(+), 1 deletion(-)
diff --git a/src/atrri.c b/src/atrri.c
@@ -19,6 +19,7 @@
 #include "atrri_c.h"
 #include "atrri_log.h"
 
+#include <rsys/algorithm.h>
 #include <rsys/cstr.h>
 #include <rsys/text_reader.h>
 
@@ -28,6 +29,21 @@
 /*******************************************************************************
  * Local functions
  ******************************************************************************/
+static INLINE int
+cmp_refractive_index(const void* key, const void* entry)
+{
+  const double wavelength = *((const double*)key);
+  const struct atrri_refractive_index* id = entry;
+
+  if(wavelength < id->wavelength) {
+    return -1;
+  } else if(wavelength > id->wavelength) {
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
 static INLINE void
 reset_atrri(struct atrri* atrri)
 {
@@ -312,3 +328,66 @@ atrri_get_desc(const struct atrri* atrri, struct atrri_desc* desc)
   desc->nindices = darray_refractive_id_size_get(&atrri->refract_ids);
   return RES_OK;
 }
+
+res_T
+atrri_fetch_refractive_index
+  (const struct atrri* atrri,
+   const double wavelength,
+   struct atrri_refractive_index* refract_id)
+{
+  struct atrri_desc desc = ATRRI_DESC_NULL;
+  struct atrri_refractive_index* found = NULL;
+  res_T res = RES_OK;
+
+  if(!atrri || wavelength < 0 || !refract_id) {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  ATRRI(get_desc(atrri, &desc));
+
+  /* Search for the registered refractive index whose corresponding wavelength
+   * is greater than or equal to the submitted wavelength */
+  found = search_lower_bound(&wavelength, desc.indices, desc.nindices,
+    sizeof(*desc.indices), cmp_refractive_index);
+
+   if(!found) {
+    /* All refractive indices are defined for wavelengths less than the
+     * submitted one. Clamp to the last registered refractive index  */
+    ASSERT(desc.nindices);
+    *refract_id = desc.indices[desc.nindices-1];
+
+  } else if(found == desc.indices) {
+    /* The submitted wavelength is less than the first wavelength for which a
+     * refractive index is registered. Clamp to the first registered refractive
+     * index */
+    *refract_id = desc.indices[0];
+
+  } else  {
+    const size_t inext = (size_t)(found - desc.indices);
+    const size_t iprev = inext - 1;
+    const struct atrri_refractive_index* next = desc.indices + inext;
+    const struct atrri_refractive_index* prev = desc.indices + iprev;
+    ASSERT(next->wavelength >= wavelength);
+    ASSERT(prev->wavelength < wavelength);
+
+    if(next->wavelength == wavelength) {
+      /* The submitted wavelength strictly match a registered wavelength */
+      *refract_id = *next;
+
+    } else {
+      /* Linearly interpolate the refractive index */
+      const double len = next->wavelength - prev->wavelength;
+      const double u = CLAMP((wavelength - prev->wavelength) / len, 0, 1);
+      ASSERT(len > 0);
+      refract_id->wavelength = wavelength;
+      refract_id->n = u*(prev->n - next->n) + next->n;
+      refract_id->kappa = u*(prev->kappa - next->kappa) + next->kappa;
+    }
+  }
+
+exit:
+  return res;
+error:
+  goto exit;
+}
diff --git a/src/atrri.h b/src/atrri.h
@@ -92,6 +92,12 @@ atrri_load_stream
    const char* stream_name); /* Can be NULL */
 
 ATRRI_API res_T
+atrri_fetch_refractive_index
+  (const struct atrri* atrri,
+   const double wavelength,
+   struct atrri_refractive_index* refract_id);
+
+ATRRI_API res_T
 atrri_get_desc
   (const struct atrri* atrri,
    struct atrri_desc* desc);
@@ -99,4 +105,3 @@ atrri_get_desc
 END_DECLS
 
 #endif /* ATRRI_H */
-