1 files changed, 65 insertions, 7 deletions
diff --git a/source/device_formula.cpp b/source/device_formula.cpp
index 5c1ca16..e21d374 100644
--- a/source/device_formula.cpp
+++ b/source/device_formula.cpp
@@ -1,28 +1,86 @@
+/**
+ * @file device_formula.cpp
+ * @brief Function for filling generator buffer using a mathematical formula.
+ * This is kept in its own file as exprtk.hpp takes forever to compile.
+ *
+ * Copyright (C) 2021 Clyne Sullivan
+ *
+ * Distributed under the GNU GPL v3 or later. You should have received a copy of
+ * the GNU General Public License along with this program.
+ * If not, see <https://www.gnu.org/licenses/>.
+ */
+
 #include "stmdsp.hpp"
-#include "exprtk.hpp"
 
 #include <algorithm>
+#include <random>
 #include <string_view>
 #include <vector>
 
-std::vector<stmdsp::dacsample_t> deviceGenLoadFormulaEval(const std::string_view formulaString)
+#ifndef STMDSP_DISABLE_FORMULAS
+
+#define exprtk_disable_comments
+#define exprtk_disable_break_continue
+#define exprtk_disable_sc_andor
+#define exprtk_disable_return_statement
+#define exprtk_disable_enhanced_features
+//#define exprtk_disable_string_capabilities
+#define exprtk_disable_superscalar_unroll
+#define exprtk_disable_rtl_io_file
+#define exprtk_disable_rtl_vecops
+//#define exprtk_disable_caseinsensitivity
+#include "exprtk.hpp"
+
+static std::random_device randomDevice;
+
+std::vector<stmdsp::dacsample_t> deviceGenLoadFormulaEval(const std::string& formulaString)
 {
     double x = 0;
 
     exprtk::symbol_table<double> symbol_table;
+    exprtk::function_compositor<double> compositor (symbol_table);
     exprtk::expression<double> expression;
     exprtk::parser<double> parser;
 
-    symbol_table.add_variable("x", x);
     symbol_table.add_constants();
+    symbol_table.add_variable("x", x);
+    symbol_table.add_function("random",
+        [](double l, double h) -> double {
+            return std::uniform_real_distribution<double>(l, h)(randomDevice);
+        });
+    compositor.add(exprtk::function_compositor<double>::function()
+                       .name("square")
+                       .var("X")
+                       .expression("ceil(sin(pi*X))"));
+    compositor.add(exprtk::function_compositor<double>::function()
+                       .name("triangle")
+                       .var("X")
+                       .expression("ceil(sin(pi*X))*(X-floor(X))+ceil(-sin(pi*X))*(-X-floor(-X))"));
+    compositor.add(exprtk::function_compositor<double>::function()
+                       .name("pulse")
+                       .var("L")
+                       .var("X")
+                       .expression("if(X<=L,1,0)"));
     expression.register_symbol_table(symbol_table);
-    parser.compile(std::string(formulaString), expression);
+    parser.compile(formulaString, expression);
+
+    const auto genFun = [&x, &expression] {
+        const auto s = std::clamp(expression.value(), -1., 1.) * 2048. + 2048.;
+        ++x;
+        return static_cast<stmdsp::dacsample_t>(std::min(s, 4095.));
+    };
 
     std::vector<stmdsp::dacsample_t> samples (stmdsp::SAMPLES_MAX);
+    std::generate(samples.begin(), samples.end(), genFun);
+    return samples;
+}
 
-    std::generate(samples.begin(), samples.end(),
-                  [&] { ++x; return static_cast<stmdsp::dacsample_t>(expression.value()); });
+#else // no formula support
 
-    return samples;
+std::vector<stmdsp::dacsample_t> deviceGenLoadFormulaEval(const std::string&)
+{
+    return {};
 }
 
+#endif // STMDSP_DISABLE_FORMULAS
+