entity ch_02_01 is
end entity ch_02_01;
----------------------------------------------------------------
architecture test of ch_02_01 is
begin
section_2_1_a : process is
-- code from book:
constant number_of_bytes : integer := 4;
constant number_of_bits : integer := 8 * number_of_bytes;
constant e : real := 2.718281828;
constant prop_delay : time := 3 ns;
constant size_limit, count_limit : integer := 255;
--
variable index : integer := 0;
variable sum, average, largest : real;
variable start, finish : time := 0 ns;
-- end of code from book
begin
wait;
end process section_2_1_a;
----------------
section_2_1_b : process is
-- code from book:
variable start : time := 0 ns;
variable finish : time := 0 ns;
-- end of code from book
variable program_counter : integer;
variable index : integer;
begin
-- code from book:
program_counter := 0;
index := index + 1;
-- end of code from book
wait;
end process section_2_1_b;
----------------
section_2_2_a : process is
-- code from book:
type apples is range 0 to 100;
type oranges is range 0 to 100;
--
type day_of_month is range 0 to 31;
type year is range 0 to 2100;
variable today : day_of_month := 9;
variable start_year : year := 1987;
--
constant number_of_bits : integer := 32;
type bit_index is range 0 to number_of_bits - 1;
--
type set_index_range is range 21 downto 11;
type mode_pos_range is range 5 to 7;
variable set_index : set_index_range;
variable mode_pos : mode_pos_range;
--
type input_level is range -10.0 to +10.0;
type probability is range 0.0 to 1.0;
--
variable input_A : input_level;
-- end of code from book
begin
-- code from book:
-- error: Incompatible types for assignment
-- start_year := today;
-- end of code from book
wait;
end process section_2_2_a;
----------------
section_2_2_b : process is
-- code from book:
type resistance is range 0 to 1E9
units
ohm;
end units resistance;
-- end of code from book
begin
wait;
end process section_2_2_b;
----------------
section_2_2_c : process is
-- code from book:
type resistance is range 0 to 1E9
units
ohm;
kohm = 1000 ohm;
Mohm = 1000 kohm;
end units resistance;
-- end of code from book
begin
wait;
end process section_2_2_c;
----------------
section_2_2_d : process is
-- code from book:
type length is range 0 to 1E9
units
um; -- primary unit: micron
mm = 1000 um; -- metric units
m = 1000 mm;
mil = 254 um; -- imperial units
inch = 1000 mil;
end units length;
-- end of code from book
begin
wait;
end process section_2_2_d;
----------------
section_2_2_e : process is
-- code from book:
-- type time is range implementation_defined
type time is range integer'low to integer'high
units
fs;
ps = 1000 fs;
ns = 1000 ps;
us = 1000 ns;
ms = 1000 us;
sec = 1000 ms;
min = 60 sec;
hr = 60 min;
end units;
-- end of code from book
begin
wait;
end process section_2_2_e;
----------------
section_2_2_f : process is
-- code from book:
type alu_function is (disable, pass, add, subtract, multiply, divide);
--
type octal_digit is ('0', '1', '2', '3', '4', '5', '6', '7');
--
variable alu_op : alu_function;
variable last_digit : octal_digit := '0';
--
type logic_level is (unknown, low, undriven, high);
variable control : logic_level;
type water_level is (dangerously_low, low, ok);
variable water_sensor : water_level;
-- end of code from book
begin
-- code from book:
alu_op := subtract;
last_digit := '7';
--
control := low;
water_sensor := low;
-- end of code from book
wait;
end process section_2_2_f;
----------------
section_2_2_g : process is
-- code from book:
type severity_level is (note, warning, error, failure);
-- end of code from book
begin
wait;
end process section_2_2_g;
----------------
section_2_2_h : process is
-- code from book:
variable cmd_char, terminator : character;
-- end of code from book
begin
-- code from book:
cmd_char := 'P';
terminator := cr;
-- end of code from book
wait;
end process section_2_2_h;
----------------
section_2_2_i : process is
-- code from book:
type boolean is (false, true);
--
type bit is ('0', '1');
-- end of code from book
begin
wait;
end process section_2_2_i;
----------------
section_2_2_j : process is
variable write_enable_n, select_reg_n, write_reg_n : bit;
begin
-- code from book:
write_reg_n := not ( not write_enable_n and not select_reg_n );
-- end of code from book
wait;
end process section_2_2_j;
----------------
section_2_2_k : process is
-- code from book:
type std_ulogic is ( 'U', -- Uninitialized
'X', -- Forcing Unknown
'0', -- Forcing zero
'1', -- Forcing one
'Z', -- High Impedance
'W', -- Weak Unknown
'L', -- Weak zero
'H', -- Weak one
'-' ); -- Don't care
-- end of code from book
begin
wait;
end process section_2_2_k;
----------------
section_2_3_a : process is
-- code from book:
subtype small_int is integer range -128 to 127;
--
variable deviation : small_int;
variable adjustment : integer;
--
subtype bit_index is integer range 31 downto 0;
-- end of code from book
begin
deviation := 0;
adjustment := 0;
-- code from book:
deviation := deviation + adjustment;
-- end of code from book
wait;
end process section_2_3_a;
----------------
section_2_3_b : process is
constant highest_integer : integer := integer'high;
constant highest_time : time := time'high;
-- code from book:
subtype natural is integer range 0 to highest_integer;
subtype positive is integer range 1 to highest_integer;
--
subtype delay_length is time range 0 fs to highest_time;
-- end of code from book
begin
wait;
end process section_2_3_b;
----------------
section_2_3_c : process is
-- code from book:
type logic_level is (unknown, low, undriven, high);
type system_state is (unknown, ready, busy);
--
subtype valid_level is logic_level range low to high;
-- end of code from book
begin
wait;
end process section_2_3_c;
----------------
section_2_4_a : process is
-- code from book:
type resistance is range 0 to 1E9
units
ohm;
kohm = 1000 ohm;
Mohm = 1000 kohm;
end units resistance;
type set_index_range is range 21 downto 11;
type logic_level is (unknown, low, undriven, high);
-- end of code from book
begin
-- output from vsim: "2000"
report resistance'image(2 kohm);
-- code from book:
assert resistance'left = 0 ohm;
assert resistance'right = 1E9 ohm;
assert resistance'low = 0 ohm;
assert resistance'high = 1E9 ohm;
assert resistance'ascending = true;
assert resistance'image(2 kohm) = "2000 ohm";
assert resistance'value("5 Mohm") = 5_000_000 ohm;
assert set_index_range'left = 21;
assert set_index_range'right = 11;
assert set_index_range'low = 11;
assert set_index_range'high = 21;
assert set_index_range'ascending = false;
assert set_index_range'image(14) = "14";
assert set_index_range'value("20") = 20;
assert logic_level'left = unknown;
assert logic_level'right = high;
assert logic_level'low = unknown;
assert logic_level'high = high;
assert logic_level'ascending = true;
assert logic_level'image(undriven) = "undriven";
assert logic_level'value("Low") = low;
--
assert logic_level'pos(unknown) = 0;
assert logic_level'val(3) = high;
assert logic_level'succ(unknown) = low;
assert logic_level'pred(undriven) = low;
--
assert time'pos(4 ns) = 4_000_000;
-- end of code from book
wait;
end process section_2_4_a;
----------------
section_2_4_b : process is
-- code from book:
type length is range integer'low to integer'high
units
mm;
end units length;
type area is range integer'low to integer'high
units
square_mm;
end units area;
--
variable L1, L2 : length;
variable A : area;
-- end of code from book
begin
-- code from book:
-- error: No feasible entries for infix op: "*"
-- A := L1 * L2; -- this is incorrect
--
A := area'val( length'pos(L1) * length'pos(L2) );
-- end of code from book
wait;
end process section_2_4_b;
----------------
section_2_4_c : process is
-- code from book:
type opcode is (nop, load, store, add, subtract, negate, branch, halt);
subtype arith_op is opcode range add to negate;
-- end of code from book
begin
-- code from book:
assert arith_op'base'left = nop;
assert arith_op'base'succ(negate) = branch;
-- end of code from book
wait;
end process section_2_4_c;
end architecture test;
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