Commit ee2fd3cc authored by Tristan Gingold's avatar Tristan Gingold

VME_CR_CSR_Space: add comments.

parent 88f59fc3
......@@ -353,11 +353,22 @@ begin
when c_BIT_CLR_REG =>
s_reg_bit_reg <= s_reg_bit_reg and not data_i;
-- VITAL-1-1 Rule 10.27
-- 4) Ownership shall be released by writing any value with
-- bit 2 set (eg 0x04) to the CSR Bit Clear Register
-- located at 0x7fff7. This clears the CRAM_OWNER
-- register and leaves it with a value of zero and also
-- clears the CRAM owned status.
if data_i(c_CRAM_OWNER_BIT) = '1' then
s_reg_cram_owner <= x"00";
end if;
when c_CRAM_OWNER_REG =>
-- VITAL-1-1 Rule 10.27
-- 2) Writing to CRAM_OWNER register when it contains a non-
-- zero value shall not change the value of the
-- CRAM_OWNER. That allows the first master that writes
-- a non-zero value to acquire ownership.
if s_reg_cram_owner = x"00" then
s_reg_cram_owner <= data_i;
s_reg_bit_reg(c_CRAM_OWNER_BIT) <= '1';
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