Module: ppl/ppl Branch: master Commit: bf625371f4d8b97edfa295b447c9245788c24585 URL: http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=bf625371f4d8b... Author: Patricia Hill <p.m.hill@leeds.ac.uk> Date: Tue May 12 17:19:02 2009 +0100 Improved documentation and small efficiency improvement to the code. --- doc/definitions.dox | 14 ++++++++------ src/Grid_public.cc | 3 +-- 2 files changed, 9 insertions(+), 8 deletions(-) diff --git a/doc/definitions.dox b/doc/definitions.dox index e3148c0..aa3839e 100644 --- a/doc/definitions.dox +++ b/doc/definitions.dox @@ -2322,9 +2322,9 @@ the given bounded integer type and have the specified overflow behavior. Suppose \f$\cL \in \Gset_n\f$ is a grid and \f$J\f$ a subset of the set of space dimensions \f$\{0, \ldots, n-1\}\f$. Suppose also that the width of the bounded integer type is \f$w\f$ so that -the range of values \f$R = \{0, \ldots, 2^w-1\}\f$ +the range of values \f$R = \{r \in \Rset \mid 0 \leq r < 2^w\}\f$ if the type is unsigned -and \f$R = \{-2^{w-1},\ldots, 0, \ldots, 2^{w-1} - 1\}\f$ otherwise. +and \f$R = \{r \in \Rset \mid -2^{w-1} \leq r < 2^{w-1}\}\f$ otherwise. Consider a space dimension \f$j \in J\f$ and a variable \f$v_j\f$ for dimension \f$j\f$. @@ -2345,11 +2345,13 @@ specified overflow behavior. Therefore the parameter \f$(0, \ldots, 0, v_j, 0, \dots, 0)\f$, where \f$v_j = 1\f$ is added to the generator system for \f$\cL\f$. -- Overflow wraps. In this case, for each value \f$a\f$ for - \f$v_j\f$ in the grid \f$\cL\f$, the wrapped value can be any value - \f$a + z 2^{w-1} \in R\f$ where \f$z \in \Zset\f$. +- Overflow wraps. In this case, if \f$v_j\f$ has exactly + one value \f$a \in R\f$ in \f$\cL\f$, then \f$v_j\f$ is set + equal to \f$a\f$. Otherwise, for each value \f$a\f$ for + \f$v_j\f$ in the grid \f$\cL\f$, there must be more than one value + of the form \f$a + z 2^w \in R\f$ where \f$z \in \Zset\f$. Therefore the parameter \f$(0, \ldots, 0, v_j, 0, \dots, 0)\f$, - where \f$v_j = 2^{w-1}\f$ is added to the generator system for \f$\cL\f$. + where \f$v_j = 2^w\f$ is added to the generator system for \f$\cL\f$. \subsection Grid_Widening Widening Operators diff --git a/src/Grid_public.cc b/src/Grid_public.cc index 677859d..844c7ec 100644 --- a/src/Grid_public.cc +++ b/src/Grid_public.cc @@ -2759,7 +2759,6 @@ PPL::Grid::wrap_assign(const Variables_Set& vars, assert(o == OVERFLOW_UNDEFINED); // If overflow is undefined, then all we know is that the variable // may take any integer within the range of the bounded integer type. - PPL_DIRTY_TEMP_COEFFICIENT(coeff_x); const Grid_Generator& point = gen_sys[0]; const Coefficient& div = point.divisor(); max_value *= div; @@ -2775,7 +2774,7 @@ PPL::Grid::wrap_assign(const Variables_Set& vars, } else { // `x' is a constant `v' in `gr'. - coeff_x = point.coefficient(x); + const Coefficient& coeff_x = point.coefficient(x); // If the value `v' for `x' is not within the range for the // bounded integer type, then `x' may wrap to any value `v + z' // where `z' is an integer; otherwise `x' is unchanged.