From 6a0885a56c660e0041e8879d96e23b27a072f23c Mon Sep 17 00:00:00 2001
From: Louis Rubet <louis@rubet.fr>
Date: Mon, 22 May 2017 14:29:55 +0200
Subject: [PATCH] #40: added command prec

---
 src/rpn-cmd.h     |  5 ++++-
 src/rpn-general.h | 22 ++++++++++++++++++++++
 src/rpn.cpp       |  9 +++++----
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/src/rpn-cmd.h b/src/rpn-cmd.h
index 116bf9a..970d739 100644
--- a/src/rpn-cmd.h
+++ b/src/rpn-cmd.h
@@ -12,8 +12,11 @@ program::keyword_t program::_keywords[] =
     { cmd_keyword, "test", &program::test, "" }, //not seen by user
     { cmd_keyword, "version", &program::rpn_version, "show rpn version" },
     { cmd_keyword, "uname", &program::rpn_uname, "show rpn complete identification string" },
-    { cmd_keyword, "type", &program::type, "show first stack entry type" },
+    { cmd_keyword, "type", &program::type, "show type of stack first entry" },
     { cmd_keyword, "default", &program::rpn_default, "set float representation and precision to default" },
+    { cmd_keyword, "prec", &program::precision, "get float precision in bits when first stack is not a number\n\t"
+                                                "set float precision in bits when first stack entry is a number. ex: 256 prec\n\t" },
+    { cmd_keyword, "round", &program::rpn_default, "set float rounding mode.\n\tex: [\"nearest\", \"toward zero\", \"toward +inf\", \"toward +inf\", \"away from zero\"] round" },
 
     //REAL
     { cmd_undef, "", NULL, "\nREAL"},
diff --git a/src/rpn-general.h b/src/rpn-general.h
index 772c755..f6e9d23 100644
--- a/src/rpn-general.h
+++ b/src/rpn-general.h
@@ -139,3 +139,25 @@ void rpn_default()
 {
     program::apply_default();
 }
+
+void precision()
+{
+    if (stack_size()>0 && _stack->get_type(0) == cmd_number)
+    {
+        //set MPFR float precision
+        long prec = mpfr_get_si(((number*)_stack->pop_back())->_value.mpfr, s_mpfr_rnd);
+        if (prec >= 0)
+        {
+            s_mpfr_prec = (mpfr_prec_t)prec;
+            s_mpfr_prec_bytes = mpfr_custom_get_size(prec);
+        }
+        else
+            ERR_CONTEXT(ret_out_of_range);
+    }
+    else
+    {
+        // get MPFR float precision
+        number* num = (number*)_stack->allocate_back(number::calc_size(), cmd_number);
+        num->set((long)s_mpfr_prec);
+    }
+}
diff --git a/src/rpn.cpp b/src/rpn.cpp
index 036e2d0..1bccc52 100644
--- a/src/rpn.cpp
+++ b/src/rpn.cpp
@@ -43,7 +43,7 @@ using namespace std;
 #define DEFAULT_PRECISION 12
 
 // MPFR related constants
-// 128 bits significand storing length in byters, result of mpfr_custom_get_size(128)
+// 128 bits significand storing length in bytes, result of mpfr_custom_get_size(128)
 #define MPFR_DEF_RND MPFR_RNDN
 #define MPFR_128BITS_PREC 128
 #define MPFR_128BITS_STORING_LENGTH 16
@@ -56,6 +56,7 @@ static string s_mpfr_printf_format_hex = "%Ra";
 static string s_mpfr_printf_format = "%.12Rg";
 static mpfr_prec_t s_mpfr_prec = MPFR_128BITS_PREC;
 static mpfr_rnd_t s_mpfr_rnd = MPFR_DEF_RND;
+static unsigned int s_mpfr_prec_bytes = MPFR_128BITS_STORING_LENGTH;
 
 //
 #include "escape.h"
@@ -106,7 +107,7 @@ struct floating_t
 
     void init(void* significand)
     {
-        mpfr_custom_init(significand, MPFR_128BITS_STORING_LENGTH);
+        mpfr_custom_init(significand, MPFR_128BITS_PREC);
         mpfr_custom_init_set(mpfr, MPFR_ZERO_KIND, 0, s_mpfr_prec, significand);
     }
 
@@ -175,7 +176,7 @@ struct number : public object
     void copy(number& op)
     {
         _value = op._value;
-        memcpy(_value.mpfr->_mpfr_d, op._value.mpfr->_mpfr_d, MPFR_128BITS_STORING_LENGTH);
+        memcpy(_value.mpfr->_mpfr_d, op._value.mpfr->_mpfr_d, s_mpfr_prec_bytes);
     }
 
     //
@@ -199,7 +200,7 @@ struct number : public object
 
     static unsigned int calc_size()
     {
-        return (unsigned int)(sizeof(number)+MPFR_128BITS_STORING_LENGTH);
+        return (unsigned int)(sizeof(number)+s_mpfr_prec_bytes);
     }
 
     //