From 7155e47537e3707d42a675d2603386963c6d9156 Mon Sep 17 00:00:00 2001
From: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Date: Fri, 13 Apr 2012 01:45:02 +0200
Subject: Support shifts with keyboard

This patch also changes the shift operation itself to use MPNumber for the
multiplier too. Previously a signed int was used, which led to "interesting" results
for bigger numbers. This was hidden because the GUI did not allow shifts with
more than 15 places.

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
---
 src/math-buttons.c       |  4 ++--
 src/mp-binary.c          | 15 ++++++++-------
 src/mp-equation-lexer.l  |  4 ++++
 src/mp-equation-parser.y |  3 +++
 4 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/math-buttons.c b/src/math-buttons.c
index fc13976..19ca08e 100644
--- a/src/math-buttons.c
+++ b/src/math-buttons.c
@@ -252,10 +252,10 @@ static ButtonData button_data[] = {
       N_("Undo [Ctrl+Z]")},
     {"shift_left", NULL, ACTION,
       /* Tooltip for the shift left button */
-      N_("Shift Left")},
+      N_("Shift Left [<<]")},
     {"shift_right", NULL, ACTION,
       /* Tooltip for the shift right button */
-      N_("Shift Right")},
+      N_("Shift Right [>>]")},
     {"finc_compounding_term", NULL, FUNCTION,
       /* Tooltip for the compounding term button */
       N_("Compounding Term")},
diff --git a/src/mp-binary.c b/src/mp-binary.c
index e4cedba..f85b3ee 100644
--- a/src/mp-binary.c
+++ b/src/mp-binary.c
@@ -167,7 +167,9 @@ mp_mask(const MPNumber *x, int wordlen, MPNumber *z)
 void
 mp_shift(const MPNumber *x, int count, MPNumber *z)
 {
-    int i, multiplier = 1;
+    int i;
+    MPNumber multiplier;
+    mp_set_from_integer(1, &multiplier);
 
     if (!mp_is_integer(x)) {
         /* Translators: Error displayed when bit shift attempted on non-integer values */
@@ -177,15 +179,14 @@ mp_shift(const MPNumber *x, int count, MPNumber *z)
 
     if (count >= 0) {
         for (i = 0; i < count; i++)
-            multiplier *= 2;
-        mp_multiply_integer(x, multiplier, z);
+            mp_multiply_integer(&multiplier, 2, &multiplier);
+        mp_multiply(x, &multiplier, z);
     }
     else {
-        MPNumber temp;
         for (i = 0; i < -count; i++)
-            multiplier *= 2;
-        mp_divide_integer(x, multiplier, &temp);
-        mp_floor(&temp, z);
+            mp_multiply_integer(&multiplier, 2, &multiplier);
+        mp_divide(x, &multiplier, z);
+        mp_floor(z, z);
     }
 }
 
diff --git a/src/mp-equation-lexer.l b/src/mp-equation-lexer.l
index bbc9765..74eb7d5 100644
--- a/src/mp-equation-lexer.l
+++ b/src/mp-equation-lexer.l
@@ -75,6 +75,8 @@ MOD  [mM][oO][dD]
 AND  "∧"|[aA][nN][dD]
 OR   "∨"|[oO][rR]
 XOR  "⊻"|"⊕"|[xX][oO][rR]
+LSHIFT  "<<"
+RSHIFT  ">>"
 NOT  "¬"|"~"|[nN][oO][tT]
 RE   "⃰ℜ"
 IM   "ℑ"
@@ -94,6 +96,8 @@ IN   [iI][nN]
 "√"         {return tROOT;}
 "∛"         {return tROOT3;}
 "∜"         {return tROOT4;}
+{LSHIFT}    {return tLSHIFT;}
+{RSHIFT}    {return tRSHIFT;}
 {NOT}       {return tNOT;}
 {AND}       {return tAND;}
 {OR}        {return tOR;}
diff --git a/src/mp-equation-parser.y b/src/mp-equation-parser.y
index 064f90f..bb623cd 100644
--- a/src/mp-equation-parser.y
+++ b/src/mp-equation-parser.y
@@ -182,6 +182,7 @@ static void do_conversion(yyscan_t yyscanner, const MPNumber *x, const char *x_u
 %left UNARY_PLUS
 %left tADD tSUBTRACT
 %left tAND tOR tXOR tXNOR
+%left tLSHIFT tRSHIFT
 %left tMULTIPLY tDIVIDE tMOD MULTIPLICATION
 %left tNOT
 %left tROOT tROOT3 tROOT4
@@ -242,6 +243,8 @@ exp:
 | exp tOR exp %prec BOOLEAN_OPERATOR {mp_or(&$1, &$3, &$$);}
 | exp tXOR exp %prec BOOLEAN_OPERATOR {mp_xor(&$1, &$3, &$$);}
 | tNUMBER {mp_set_from_mp(&$1, &$$);}
+| exp tLSHIFT exp {mp_shift(&$1, mp_cast_to_int(&$3), &$$);}
+| exp tRSHIFT exp {mp_shift(&$1, -mp_cast_to_int(&$3), &$$);}
 ;
 
 
-- 
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