fpga:vhdl
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Table of Contents
VHDL
Basics
Time suffixes
| fs | femtoseconds |
| ps | picoseconds |
| ns | nanoseconds |
| us | microseconds |
| ms | milliseconds |
| sec | seconds |
| min | minutes |
| hr | hours |
Conversions
library ieee; use ieee.std_logic_1164.all; -- std_logic_vector use ieee.numeric_std.all; -- signed and unsigned -- numbers, math operations allowed signal my_int : integer; -- 32 bit 2-complement signal my_uint : unsigned (7 downto 0); signal my_sint : signed (7 downto 0); -- loose bits, math operations not allowed signal my_bits : std_logic_vector (7 downto 0); -- conversions between integers my_uint <= to_unsigned(my_int, 8); -- Must specify bit length my_sint <= to_signed(my_int, 8); my_int <= to_integer(my_uint); my_int <= to_integer(my_sint); -- casts between binary representations, number of bits must match my_uint <= unsigned(my_sint); my_uint <= unsigned(my_bits); my_sint <= signed(my_uint); my_sint <= signed(my_bits); my_bits <= std_logic_vector(my_uint); my_bits <= std_logic_vector(my_sint);
Simulation only stuff
Time based stuff
-- after statements can be chained in the concurrent scope as such: reset <= '0', '1' after 20 us, '0' after 40 us, '1' after 300 us, '0' after 320 us;
fpga/vhdl.1641475894.txt.gz · Last modified: 2022/09/12 00:30 (external edit)
