You can see it live here:
;A very advanced example: Implementing the permutations algorithm in PicoBlaze assembly. base_decimal constant NDEBUG, 1 constant address_of_the_current_attempt, 8 constant bottom_of_the_stack, 16 address 0 namereg sf, length_of_the_input call print_the_introduction_message load length_of_the_input, 0 beginning_of_the_input_loop: call UART_RX compare s9, a'x ;The new-line character. jump z, end_of_the_input_loop store s9, (length_of_the_input) add length_of_the_input, 1 jump beginning_of_the_input_loop end_of_the_input_loop: compare length_of_the_input, 0 jump z, 0 beginning_of_the_bubble_sort: load s4, 0 ;A boolean indicating ;whether a swap has been ;performed. load s0, 0 inner_bubble_sort_loop: load s1, length_of_the_input sub s1, 1 compare s0, s1 jump nc, end_of_the_inner_bubble_sort_loop load s1, s0 add s1, 1 fetch s2, (s0) fetch s3, (s1) compare s3, s2 jump nc, do_not_swap store s3, (s0) store s2, (s1) load s4, 1 do_not_swap: add s0, 1 jump inner_bubble_sort_loop end_of_the_inner_bubble_sort_loop: compare s4, 0 jump nz, beginning_of_the_bubble_sort end_of_the_bubble_sort_loop: jump NDEBUG ? the_permutations_algorithm : printing_the_sorted_array printing_the_sorted_array: call print_the_sorted_array_message load s0, 0 printing_the_sorted_array_loop: compare s0, length_of_the_input jump nc, end_of_the_printing_the_sorted_array_loop fetch s9, (s0) call UART_TX add s0, 1 jump printing_the_sorted_array_loop end_of_the_printing_the_sorted_array_loop: load s9, a'x call UART_TX the_permutations_algorithm: namereg se, top_of_the_stack load top_of_the_stack, bottom_of_the_stack load s0, 0 store s0, (top_of_the_stack) add top_of_the_stack, length_of_the_input add top_of_the_stack, 1 beginning_of_the_permutations_loop: compare top_of_the_stack, bottom_of_the_stack jump z, end_of_the_permutations_loop sub top_of_the_stack, length_of_the_input sub top_of_the_stack, 1 namereg sd, length_of_the_current_attempt fetch length_of_the_current_attempt, (top_of_the_stack) load s0, address_of_the_current_attempt store length_of_the_current_attempt, (s0) load s1, 0 copying_the_current_attempt_from_the_stack_loop: compare s1, length_of_the_current_attempt jump nc, end_of_copying load s0, address_of_the_current_attempt add s0, s1 add s0, 1 load s3, top_of_the_stack add s3, s1 add s3, 1 fetch s4, (s3) store s4, (s0) add s1, 1 jump copying_the_current_attempt_from_the_stack_loop end_of_copying: jump NDEBUG ? dont_print_the_current_attempt : print_the_current_attempt print_the_current_attempt: call print_the_length_of_the_current_attempt_message load s9, length_of_the_current_attempt add s9, "0" call UART_TX load s9, a'x call UART_TX call print_the_current_attempt_message load s0, address_of_the_current_attempt + 1 printing_the_current_attempt_loop: load s1, address_of_the_current_attempt + 1 add s1, length_of_the_current_attempt compare s0, s1 jump nc, end_of_the_printing_the_current_attempt_loop fetch s9, (s0) call UART_TX add s0, 1 jump printing_the_current_attempt_loop end_of_the_printing_the_current_attempt_loop: load s9, a'x call UART_TX dont_print_the_current_attempt: compare length_of_the_current_attempt, length_of_the_input jump c, current_attempt_is_not_a_solution call print_found_a_solution_message load s0, address_of_the_current_attempt + 1 printing_the_solution_loop: load s1, address_of_the_current_attempt + 1 add s1, length_of_the_current_attempt compare s0, s1 jump nc, end_of_the_printing_the_solution_loop fetch s9, (s0) call UART_TX add s0, 1 jump printing_the_solution_loop end_of_the_printing_the_solution_loop: load s9, a'x call UART_TX jump end_of_the_branching current_attempt_is_not_a_solution: load s0, length_of_the_input sub s0, 1 add_a_new_character_loop: compare s0, ff'x ;Overflow jump z, end_of_the_add_a_new_character_loop namereg sc, character_we_try_to_add fetch character_we_try_to_add, (s0) load s7, s0 add s7, 1 load s8, 0 ;Whether we already tried adding that character. check_if_we_already_tried_that_character_loop: compare s7, length_of_the_input jump nc, end_of_the_check_if_we_already_tried_that_character_loop fetch s6, (s7) compare s6, character_we_try_to_add jump nz, third_characters_are_not_equal_label load s8, 1 third_characters_are_not_equal_label: add s7, 1 jump check_if_we_already_tried_that_character_loop end_of_the_check_if_we_already_tried_that_character_loop: test s8, s8 jump nz, dont_add_the_new_character jump NDEBUG ? dont_print_the_character_we_are_trying_to_add : print_the_character_we_are_trying_to_add print_the_character_we_are_trying_to_add: call print_we_are_trying_to_add_message load s9, character_we_try_to_add call UART_TX load s9, a'x call UART_TX dont_print_the_character_we_are_trying_to_add: load s2, 0 ; How many of the chosen character are present in the current attempt. load s1, address_of_the_current_attempt + 1 count_in_the_current_attempt_loop: load s4, address_of_the_current_attempt + 1 add s4, length_of_the_current_attempt compare s1, s4 jump z, end_of_the_count_in_the_current_attempt_loop fetch s4, (s1) compare s4, character_we_try_to_add jump nz, first_the_characters_are_not_equal_label add s2, 1 first_the_characters_are_not_equal_label: add s1, 1 jump count_in_the_current_attempt_loop end_of_the_count_in_the_current_attempt_loop: jump NDEBUG ? dont_print_how_many_in_the_current_attempt : print_how_many_in_the_current_attempt print_how_many_in_the_current_attempt: call print_the_current_attempt_count_message load s9, s2 add s9, "0" call UART_TX load s9, a'x call UART_TX dont_print_how_many_in_the_current_attempt: load s3, 0 ; How many of the chosen character are present in the input. load s1, 0 count_in_the_input_loop: compare s1, length_of_the_input jump z, end_of_the_count_in_the_input_loop fetch s4, (s1) compare s4, character_we_try_to_add jump nz, second_the_characters_are_not_equal_label add s3, 1 second_the_characters_are_not_equal_label: add s1, 1 jump count_in_the_input_loop end_of_the_count_in_the_input_loop: jump NDEBUG ? dont_print_how_many_in_the_input : print_how_many_in_the_input print_how_many_in_the_input: call print_count_in_the_input_message load s9, s3 add s9, "0" call UART_TX load s9, a'x call UART_TX dont_print_how_many_in_the_input: compare s2, s3 jump nc, dont_add_the_new_character load s1, NDEBUG test s1, s1 call z, print_the_we_are_adding_the_new_character_message load s1, top_of_the_stack load s2, length_of_the_current_attempt add s2, 1 store s2, (s1) add s1, 1 load s3, address_of_the_current_attempt + 1 copying_the_new_attempt_loop: load s5, address_of_the_current_attempt + 1 add s5, length_of_the_current_attempt compare s3, s5 jump z, end_of_the_copying_the_new_attempt_loop fetch s4, (s3) store s4, (s1) add s3, 1 add s1, 1 jump copying_the_new_attempt_loop end_of_the_copying_the_new_attempt_loop: load s1, top_of_the_stack add s1, length_of_the_current_attempt add s1, 1 store character_we_try_to_add, (s1) add top_of_the_stack, length_of_the_input add top_of_the_stack, 1 dont_add_the_new_character: sub s0, 1 jump add_a_new_character_loop end_of_the_add_a_new_character_loop: jump end_of_the_branching end_of_the_branching: jump beginning_of_the_permutations_loop end_of_the_permutations_loop: call print_the_end_message jump 0 print_the_introduction_message: load s9, "E" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, " " call UART_TX load s9, "s" call UART_TX load s9, "h" call UART_TX load s9, "o" call UART_TX load s9, "r" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "s" call UART_TX load s9, "t" call UART_TX load s9, "r" call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, "g" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "n" call UART_TX load s9, "d" call UART_TX load s9, " " call UART_TX load s9, "p" call UART_TX load s9, "r" call UART_TX load s9, "e" call UART_TX load s9, "s" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX load s9, "e" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, "." call UART_TX load s9, a'x call UART_TX return print_the_sorted_array_message: load s9, "A" call UART_TX load s9, "f" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "B" call UART_TX load s9, "u" call UART_TX load s9, "b" call UART_TX load s9, "b" call UART_TX load s9, "l" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "S" call UART_TX load s9, "o" call UART_TX load s9, "r" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "l" call UART_TX load s9, "g" call UART_TX load s9, "o" call UART_TX load s9, "r" call UART_TX load s9, "i" call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "m" call UART_TX load s9, "," call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, "p" call UART_TX load s9, "u" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "s" call UART_TX load s9, "t" call UART_TX load s9, "r" call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, "g" call UART_TX load s9, " " call UART_TX load s9, "l" call UART_TX load s9, "o" call UART_TX load s9, "o" call UART_TX load s9, "k" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX load s9, "l" call UART_TX load s9, "i" call UART_TX load s9, "k" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "i" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX return print_the_current_attempt_message: load s9, "T" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "u" call UART_TX load s9, "r" call UART_TX load s9, "r" call UART_TX load s9, "e" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "m" call UART_TX load s9, "p" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX return print_we_are_trying_to_add_message: load s9, "W" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "r" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "r" call UART_TX load s9, "y" call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, "g" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "o" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "d" call UART_TX load s9, "d" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "r" call UART_TX load s9, "a" call UART_TX load s9, "c" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, " " call UART_TX return print_the_current_attempt_count_message: load s9, "T" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "o" call UART_TX load s9, "u" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "o" call UART_TX load s9, "f" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "r" call UART_TX load s9, "a" call UART_TX load s9, "c" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "u" call UART_TX load s9, "r" call UART_TX load s9, "r" call UART_TX load s9, "e" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "m" call UART_TX load s9, "p" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX return print_count_in_the_input_message: load s9, "T" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "o" call UART_TX load s9, "u" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "o" call UART_TX load s9, "f" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "r" call UART_TX load s9, "a" call UART_TX load s9, "c" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, "p" call UART_TX load s9, "u" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "s" call UART_TX load s9, "t" call UART_TX load s9, "r" call UART_TX load s9, "i" call UART_TX load s9, "n" call UART_TX load s9, "g" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX return print_the_we_are_adding_the_new_character_message: load s9, "W" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "w" call UART_TX load s9, "i" call UART_TX load s9, "l" call UART_TX load s9, "l" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "r" call UART_TX load s9, "y" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "o" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "d" call UART_TX load s9, "d" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "h" call UART_TX load s9, "a" call UART_TX load s9, "r" call UART_TX load s9, "a" call UART_TX load s9, "c" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, "." call UART_TX load s9, a'x call UART_TX return print_found_a_solution_message: load s9, "F" call UART_TX load s9, "o" call UART_TX load s9, "u" call UART_TX load s9, "n" call UART_TX load s9, "d" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, " " call UART_TX load s9, "p" call UART_TX load s9, "e" call UART_TX load s9, "r" call UART_TX load s9, "m" call UART_TX load s9, "u" call UART_TX load s9, "t" call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, "i" call UART_TX load s9, "o" call UART_TX load s9, "n" call UART_TX load s9, " " call UART_TX return print_the_end_message: load s9, "T" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "e" call UART_TX load s9, "n" call UART_TX load s9, "d" call UART_TX load s9, "!" call UART_TX load s9, a'x call UART_TX return print_the_length_of_the_current_attempt_message: load s9, "T" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "l" call UART_TX load s9, "e" call UART_TX load s9, "n" call UART_TX load s9, "g" call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, " " call UART_TX load s9, "o" call UART_TX load s9, "f" call UART_TX load s9, " " call UART_TX load s9, "t" call UART_TX load s9, "h" call UART_TX load s9, "e" call UART_TX load s9, " " call UART_TX load s9, "c" call UART_TX load s9, "u" call UART_TX load s9, "r" call UART_TX load s9, "r" call UART_TX load s9, "e" call UART_TX load s9, "n" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "a" call UART_TX load s9, "t" call UART_TX load s9, "t" call UART_TX load s9, "e" call UART_TX load s9, "m" call UART_TX load s9, "p" call UART_TX load s9, "t" call UART_TX load s9, " " call UART_TX load s9, "i" call UART_TX load s9, "s" call UART_TX load s9, " " call UART_TX return ;Now follows some boilerplate code ;we use in our Computer Architecture ;classes... CONSTANT LED_PORT, 00 CONSTANT HEX1_PORT, 01 CONSTANT HEX2_PORT, 02 CONSTANT UART_TX_PORT, 03 CONSTANT UART_RESET_PORT, 04 CONSTANT SW_PORT, 00 CONSTANT BTN_PORT, 01 CONSTANT UART_STATUS_PORT, 02 CONSTANT UART_RX_PORT, 03 ; Tx data_present CONSTANT U_TX_D, 00000001'b ; Tx FIFO half_full CONSTANT U_TX_H, 00000010'b ; TxFIFO full CONSTANT U_TX_F, 00000100'b ; Rxdata_present CONSTANT U_RX_D, 00001000'b ; RxFIFO half_full CONSTANT U_RX_H, 00010000'b ; RxFIFO full CONSTANT U_RX_F, 00100000'b UART_RX: INPUT sA, UART_STATUS_PORT TEST sA, U_RX_D JUMP NZ, input_not_empty LOAD s0, s0 JUMP UART_RX input_not_empty: INPUT s9, UART_RX_PORT RETURN UART_TX: INPUT sA, UART_STATUS_PORT TEST sA, U_TX_F JUMP NZ, UART_TX OUTPUT s9, UART_TX_PORT RETURN As far as I've tested it, it seems to work. But I am not sure how legible it is. I've tried to make it as legible as possible by using long label names and using nameregs sometimes, as well as code indentation.
