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vhdlpp: Support for accessing words in constant arrays.

This commit is contained in:
Maciej Suminski 2015-02-19 17:04:04 +01:00
parent 0f0bef32f2
commit 9ca754b6db
1 changed files with 75 additions and 1 deletions
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76
vhdlpp/expression_elaborate.cc
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@ -922,13 +922,87 @@ const VType* ExpName::fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*)co
return probe_type(ent, scope);
}
int ExpName::elaborate_expr(Entity*, ScopeBase*, const VType*ltype)
int ExpName::elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype)
{
const VType*type = NULL;
Expression*exp = NULL;
if (ltype) {
ivl_assert(*this, ltype != 0);
set_type(ltype);
}
// Currently constant arrays of vectors are flattened to single one-dimensional
// localparams. If the user wants to access a particular word, then it is
// necessary to extract the adequate part of the localparam.
// e.g.
// declarations:
// == VHDL ==
// type uns_array is array (natural range <>) of unsigned(7 downto 0);
// constant const_array : uns_array(2 downto 0) :=
// (0 => "00110011", 1 => "101010101", 2=> "00001111");
// == SystemVerilog ==
// localparam const_array = { 8'b00110011, 8'b10101010, 8'b00001111 };
//
// access:
// == VHDL ==
// target_var := const_array(1);
// == SystemVerilog ==
// target_var = const_array[15:8]; // <- indices adjusted to pick the word
if(index_ && scope) {
if(!scope->find_constant(name_, type, exp))
return 0;
const VTypeArray*arr = dynamic_cast<const VTypeArray*>(type);
ivl_assert(*this, arr); // if there is an index, it should be an array, right?
const VType*element = arr->element_type();
const VTypeArray*arr_element = dynamic_cast<const VTypeArray*>(element);
if(!arr_element) {
// index adjustments are not necessary, it is not an array of vectors
return 0;
}
ivl_assert(*this, arr_element->dimensions() == 1);
if(arr_element->dimensions() != 1) {
cerr << get_fileline() << ": Sorry, only one-dimensional constant arrays are handled." << endl;
return 1;
}
int64_t start_val;
bool start_rc = arr_element->dimension(0).msb()->evaluate(ent, scope, start_val);
int64_t finish_val;
bool finish_rc = arr_element->dimension(0).lsb()->evaluate(ent, scope, finish_val);
if(!start_rc || !finish_rc) {
cerr << get_fileline() << ": Could not evaluate the word size." << endl;
return 1;
}
int word_size = abs(start_val - finish_val) + 1;
ExpInteger*size = new ExpInteger(word_size);
Expression*new_index, *new_lsb;
// new indices = [index_ * word_size + word_size : lsb_ * word_size]
if(lsb_) {
ExpArithmetic*tmp = new ExpArithmetic(ExpArithmetic::MULT, index_->clone(), size->clone());
new_index = new ExpArithmetic(ExpArithmetic::PLUS, tmp, size->clone());
new_lsb = new ExpArithmetic(ExpArithmetic::MULT, lsb_->clone(), size->clone());
} else {
new_lsb = new ExpArithmetic(ExpArithmetic::MULT, index_->clone(), size->clone());
new_index = new ExpArithmetic(ExpArithmetic::PLUS, new_lsb->clone(), size->clone());
}
delete index_;
delete lsb_;
delete size;
index_ = new_index;
lsb_ = new_lsb;
}
return 0;
}