...

cxx/mcc_mount_pec.h

@@ -12,6 +12,65 @@
 #include "mcc_mount_concepts.h"
 #include "mcc_mount_coord.h"
 
+namespace mcc
+{
+
+enum class MccMountDefaultPECErrorCode : int { ERROR_OK, ERROR_INVALID_INPUTS_BISPLEV, ERROR_EXCEED_MAX_ITERS };
+
+/*  error category definition  */
+
+// error category
+struct MccMountDefaultPECCategory : public std::error_category {
+    MccMountDefaultPECCategory() : std::error_category() {}
+
+    const char* name() const noexcept
+    {
+        return "ADC_GENERIC_DEVICE";
+    }
+
+    std::string message(int ec) const
+    {
+        MccMountDefaultPECErrorCode err = static_cast<MccMountDefaultPECErrorCode>(ec);
+
+        switch (err) {
+            case MccMountDefaultPECErrorCode::ERROR_OK:
+                return "OK";
+            case MccMountDefaultPECErrorCode::ERROR_INVALID_INPUTS_BISPLEV:
+                return "invalid input arguments for bispev";
+            case MccMountDefaultPECErrorCode::ERROR_EXCEED_MAX_ITERS:
+                return "exceed maximum of iterations number";
+            default:
+                return "UNKNOWN";
+        }
+    }
+
+    static const MccMountDefaultPECCategory& get()
+    {
+        static const MccMountDefaultPECCategory constInst;
+        return constInst;
+    }
+};
+
+
+inline std::error_code make_error_code(MccMountDefaultPECErrorCode ec)
+{
+    return std::error_code(static_cast<int>(ec), MccMountDefaultPECCategory::get());
+}
+}  // namespace mcc
+
+
+namespace std
+{
+
+template <>
+class is_error_code_enum<mcc::MccMountDefaultPECErrorCode> : public true_type
+{
+};
+
+}  // namespace std
+
+
+
 namespace mcc
 {
 
@@ -165,7 +224,7 @@ public:
                 if (ret) {
                     res.dx = std::numeric_limits<double>::quiet_NaN();
                     res.dy = std::numeric_limits<double>::quiet_NaN();
-                    return std::error_code();  // !!!!!!!!!!!!!!
+                    return MccMountDefaultPECErrorCode::ERROR_INVALID_INPUTS_BISPLEV;
                 }
 
 
@@ -175,7 +234,7 @@ public:
                 if (ret) {
                     res.dx = std::numeric_limits<double>::quiet_NaN();
                     res.dy = std::numeric_limits<double>::quiet_NaN();
-                    return std::error_code();  // !!!!!!!!!!!!!!
+                    return MccMountDefaultPECErrorCode::ERROR_INVALID_INPUTS_BISPLEV;
                 }
 
 
@@ -187,7 +246,7 @@ public:
             static_assert(false, "UNSUPPORTED");
         }
 
-        return std::error_code();
+        return MccMountDefaultPECErrorCode::ERROR_OK;
     }
 
     // from celestial to encoder (use of iterative scheme)
@@ -196,35 +255,59 @@ public:
         coord_t e2 = eps * eps;
 
         coord_t xi = x, yi = y;
-        coord_t xp, yp;
+        coord_t xe, ye;
         size_t iter = 1;
 
         // the first iteration
         auto err = compute(x, y, res);
 
         if (!err) {
-            xp = x - res.dx;
-            yp = y - res.dy;
+            // 'encoder' cocordinates
+            xe = x - res.dx;
+            ye = y - res.dy;
 
-            bool ok = ((xp - x) * (xp - x) + (yp - y) * (yp - y)) <= e2;
+            err = compute(xe, ye, res);  // to celestial
+            if (err) {
+                return MccMountDefaultPECErrorCode::ERROR_INVALID_INPUTS_BISPLEV;
+            }
+
+            xi = xe + res.dx;  // celestial
+            yi = ye + res.dy;
+
+            auto rx = (x - xi);
+            auto ry = (y - yi);
+            auto d = rx * rx + ry * ry;
+
+            bool ok = d <= e2;
             if (ok) {
-                return std::error_code();
+                return MccMountDefaultPECErrorCode::ERROR_OK;
             }
 
             while (iter < max_iter) {
-                xi = xp;
-                yi = xp;
-                err = compute(xi, yi, res);
-                xp -= res.dx;
-                yp -= res.dy;
-
-                ok = ((xp - xi) * (xp - xi) + (yp - yi) * (yp - yi)) <= e2;
-                if (ok) {
-                    return std::error_code();
+                err = compute(xi, yi, res);  // to encoder
+                if (err) {
+                    return MccMountDefaultPECErrorCode::ERROR_INVALID_INPUTS_BISPLEV;
                 }
+                xe = x - res.dx;
+                ye = y - res.dy;
+
+                err = compute(xe, ye, res);  // to celestial
+                if (err) {
+                    return MccMountDefaultPECErrorCode::ERROR_INVALID_INPUTS_BISPLEV;
+                }
+
+                xi = xe + res.dx;  // celestial
+                yi = ye + res.dy;
+
+                ok = ((x - xi) * (x - xi) + (y - yi) * (y - yi)) <= e2;
+                if (ok) {
+                    return MccMountDefaultPECErrorCode::ERROR_OK;
+                }
+
+                ++iter;
             }
 
-            // err = "exceed max iterations";!!!
+            err = MccMountDefaultPECErrorCode::ERROR_EXCEED_MAX_ITERS;
         }
 
         return err;