# This source file is licensed under the BSD Zero-Clause License.
# You are free to use, modify, and distribute this file without restriction.
# See LICENSE-BSD-0.txt for details.

########################
## Set Up Environment ##
########################

# Compile ALU design
vlog alu.sv

# Start graphical simulation
vsim -gui work.alu

# Restart simulation without prompt or messages
restart -force -nolog

# View waveform diagram in its own window
view wave

################
## Add Inputs ##
################

add wave -divider Inputs
add wave -group Inputs -radix hexadecimal sim:/alu/x
add wave -group Inputs -radix hexadecimal sim:/alu/y
add wave -group Inputs -group Control     sim:/alu/zx
add wave -group Inputs -group Control     sim:/alu/nx
add wave -group Inputs -group Control     sim:/alu/zy
add wave -group Inputs -group Control     sim:/alu/ny
add wave -group Inputs -group Control     sim:/alu/fn
add wave -group Inputs -group Control     sim:/alu/no

############################
## Add Intermediate Logic ##
############################

add wave -divider Intermediate
add wave -group Intermediate -radix hexadecimal sim:/alu/zeroed_x
add wave -group Intermediate -radix hexadecimal sim:/alu/zeroed_y
add wave -group Intermediate -radix hexadecimal sim:/alu/final_x
add wave -group Intermediate -radix hexadecimal sim:/alu/final_y
add wave -group Intermediate -radix hexadecimal sim:/alu/output_and
add wave -group Intermediate -radix hexadecimal sim:/alu/output_add
add wave -group Intermediate                    sim:/alu/add_overflow
add wave -group Intermediate -radix hexadecimal sim:/alu/output_raw

#################
## Add Outputs ##
#################

add wave -divider Outputs
add wave -group Outputs -radix hexadecimal sim:/alu/out
add wave -group Outputs -group Flags       sim:/alu/zr
add wave -group Outputs -group Flags       sim:/alu/ng
add wave -group Outputs -group Flags       sim:/alu/ov

#####################
## Add Two Numbers ##
#####################

# Adds 0x20 + 0x47, expected output should be 0x67

force x 16'h0020
force y 16'h0047
force zx 0
force nx 0
force zy 0
force ny 0
force fn 1
force no 0
run 10

######################
## Extract Low Byte ##
######################

# Get low byte of x by ANDing with 0x00ff
# Computes 0x9D95 & 0x00ff. Sets highest 8 bits to 0
#    1001 1101 1001 0101  (0x9D95)
#  & 0000 0000 1111 1111  (0x00ff)
# ----------------------
#    0000 0000 1001 0101  (0x0095)

force x 16'h9D95
force y 16'h00FF
force zx 0
force nx 0
force zy 0
force ny 0
force fn 0
force no 0
run 10

################
## Bitwise OR ##
################

# x | y = ~(~x & ~y)
# Computes 0x5555 | 0x003f. Sets lowest 6 bits high.
#    0101 0101 0101 0101  (0x5555)
#  | 0000 0000 0011 1111  (0x003f)
# ----------------------
#    0101 0101 0111 1111  (0x557f)

force x 16'h5555
force y 16'h003f
force zx 0
force nx 1
force zy 0
force ny 1
force fn 0
force no 1
run 10

#########################
## Compare Two Numbers ##
#########################

# Compare by subtracting then checking flags

# Subtraction x - y = ~(~x + y)
force zx 0
force nx 1
force zy 0
force ny 0
force fn 1
force no 1

# x = y; Positive
force x 16'h5A5A
force y 16'h5A5A
run 10

# x < y; Positive
force y 16'h6A6A
run 10

# x > y; Positive
force y 16'h005A
run 10

# x = y; Negative
force x 16'hA5A5
force y 16'hA5A5
run 10

# x < y; Negative
force y 16'hA6A6
run 10

# x > y; Negative
force y 16'h00A5
run 10