From 554cd971450dcb137dc8450cc42f8dfaa6cf0501 Mon Sep 17 00:00:00 2001
From: Landon Curt Noll <github-mail@asthe.com>
Date: Tue, 7 Sep 2021 07:59:51 -0700
Subject: [PATCH] Initial code for g2d() & d2g() builtins

We still need to add:

    help files for g2d & d2g
    regression tests for g2d & d2g
    notes in related trig help files
    note in unexpected help file
    note in CHANGES
---
 calcerr.tbl |  2 ++
 func.c      | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 qmath.c     |  5 +++-
 qmath.h     |  3 ++-
 4 files changed, 78 insertions(+), 2 deletions(-)

diff --git a/calcerr.tbl b/calcerr.tbl
index d22a2f2..a6fbf89 100644
--- a/calcerr.tbl
+++ b/calcerr.tbl
@@ -504,3 +504,5 @@ E_G2R1		Bad epsilon for converting gradians to radians
 E_G2R2		Bad first argument converting gradians to radians
 E_R2G1		Bad epsilon for converting radians to gradians
 E_R2G2		Bad first argument converting radians to gradians
+E_D2G1		Bad first argument converting degrees to gradians
+E_G2D1		Bad first argument converting gradians to degrees
diff --git a/func.c b/func.c
index 93dca01..9210276 100644
--- a/func.c
+++ b/func.c
@@ -2349,6 +2349,72 @@ f_r2g(int count, VALUE **vals)
 }
 
 
+/*
+ * f_d2g - convert degrees to gradians
+ *
+ * NOTE: The epsilon (vals[1]->v_num) argument is ignored.
+ */
+/*ARGSUSED*/
+S_FUNC VALUE
+f_d2g(int UNUSED(count), VALUE **vals)
+{
+	VALUE result;
+
+	/* initialize VALUE */
+	result.v_subtype = V_NOSUBTYPE;
+
+	/* NOTE: the epsilon (vals[1]->v_num) argument is ignored */
+
+	/* calculate argument * (10/9) */
+	switch (vals[0]->v_type) {
+		case V_NUM:
+			result.v_num = qmul(vals[0]->v_num, &_qtendivnine_);
+			result.v_type = V_NUM;
+			break;
+		case V_COM:
+			result.v_com = c_mulq(vals[0]->v_com, &_qtendivnine_);
+			result.v_type = V_COM;
+			break;
+		default:
+			return error_value(E_D2G1);
+	}
+	return result;
+}
+
+
+/*
+ * f_g2d - convert gradians to degrees
+ *
+ * NOTE: The epsilon (vals[1]->v_num) argument is ignored.
+ */
+/*ARGSUSED*/
+S_FUNC VALUE
+f_g2d(int UNUSED(count), VALUE **vals)
+{
+	VALUE result;
+
+	/* initialize VALUE */
+	result.v_subtype = V_NOSUBTYPE;
+
+	/* NOTE: the epsilon (vals[1]->v_num) argument is ignored */
+
+	/* calculate argument * (9/10) */
+	switch (vals[0]->v_type) {
+		case V_NUM:
+			result.v_num = qmul(vals[0]->v_num, &_qninedivten_);
+			result.v_type = V_NUM;
+			break;
+		case V_COM:
+			result.v_com = c_mulq(vals[0]->v_com, &_qninedivten_);
+			result.v_type = V_COM;
+			break;
+		default:
+			return error_value(E_G2D1);
+	}
+	return result;
+}
+
+
 S_FUNC VALUE
 f_sin(int count, VALUE **vals)
 {
@@ -8838,6 +8904,8 @@ STATIC CONST struct builtin builtins[] = {
 	 "date and time as string"},
 	{"custom", 0, IN, 0, OP_NOP, 0, f_custom,
 	 "custom builtin function interface"},
+	{"d2g", 1, 2, 0, OP_NOP, 0, f_d2g,
+	 "convert degrees to gradians"},
 	{"d2r", 1, 2, 0, OP_NOP, 0, f_d2r,
 	 "convert degrees to radians"},
 	{"delete", 2, 2, FA, OP_NOP, 0, f_listdelete,
@@ -8950,6 +9018,8 @@ STATIC CONST struct builtin builtins[] = {
 	 "return the file position"},
 	{"frac", 1, 1, 0, OP_FRAC, qfrac, 0,
 	 "fractional part of value"},
+	{"g2d", 1, 2, 0, OP_NOP, 0, f_g2d,
+	 "convert gradians to degrees"},
 	{"g2r", 1, 2, 0, OP_NOP, 0, f_g2r,
 	 "convert gradians to radians"},
 	{"gcd", 1, IN, 0, OP_NOP, f_gcd, 0,
diff --git a/qmath.c b/qmath.c
index 4c95359..963d6f3 100644
--- a/qmath.c
+++ b/qmath.c
@@ -44,9 +44,12 @@ NUMBER _qnegone_ =	{ { _oneval_, 1, 1 }, { _oneval_, 1, 0 }, 1, NULL };
 NUMBER _qonehalf_ =	{ { _oneval_, 1, 0 }, { _twoval_, 1, 0 }, 1, NULL };
 NUMBER _qneghalf_ = 	{ { _oneval_, 1, 1 }, { _twoval_, 1, 0 }, 1, NULL };
 NUMBER _qonesqbase_ =	{ { _oneval_, 1, 0 }, { _sqbaseval_, 2, 0 }, 1, NULL };
+NUMBER _qtendivnine_ =	{ { _tenval_, 1, 0 }, { _nineval_, 1, 0 }, 1, NULL };
+NUMBER _qninedivten_ =	{ { _nineval_, 1, 0 }, { _tenval_, 1, 0 }, 1, NULL };
 
 NUMBER * initnumbs[INITCONSTCOUNT] = {&_qzero_, &_qone_, &_qtwo_, &_qthree_,
-	&_qfour_, &_qten_, &_qnegone_, &_qonehalf_, &_qneghalf_};
+	&_qfour_, &_qten_, &_qnegone_, &_qonehalf_, &_qneghalf_,
+	&_qonesqbase_, &_qtendivnine_, &_qninedivten_ };
 
 
 /*
diff --git a/qmath.h b/qmath.h
index f19f4d6..1a33e33 100644
--- a/qmath.h
+++ b/qmath.h
@@ -35,7 +35,7 @@
 #endif
 
 
-#define INITCONSTCOUNT 9    /* number of initnumbs[] pre-defined constants */
+#define INITCONSTCOUNT 12    /* number of initnumbs[] pre-defined constants */
 
 /*
  * Rational arithmetic definitions.
@@ -275,6 +275,7 @@ static inline NUMBER* qlink(NUMBER* q) { if(q) { (q)->links++; } return q; }
  */
 EXTERN NUMBER _qzero_, _qone_, _qnegone_, _qonehalf_, _qneghalf_, _qonesqbase_;
 EXTERN NUMBER _qtwo_, _qthree_, _qfour_, _qten_;
+EXTERN NUMBER _qtendivnine_, _qninedivten_;
 EXTERN NUMBER * initnumbs[];