Forth Implementation, Part 4 | Bitwise Episode Guide

0:08Recap and set the stage for the day

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0:08Recap and set the stage for the day

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0:08Recap and set the stage for the day

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1:48Review the addition of "key" word and renaming of "xt" to ">cfa"

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1:48Review the addition of "key" word and renaming of "xt" to ">cfa"

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1:48Review the addition of "key" word and renaming of "xt" to ">cfa"

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5:42Run it to demo the FORTH program execution

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5:42Run it to demo the FORTH program execution

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5:42Run it to demo the FORTH program execution

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6:39Modes in FORTH: immediate vs compilation

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6:39Modes in FORTH: immediate vs compilation

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6:39Modes in FORTH: immediate vs compilation

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11:43Mode-agnostic immediate words

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11:43Mode-agnostic immediate words

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11:43Mode-agnostic immediate words

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12:52Dive into implementing modes

13:36Introduce a _push_latest word that initialises variables

15:19Introduce mode and cp labels, and "cp" word, establishing the convention that all constants are upper case

20:01Dive into implementing the ability to dynamically define dictionary entries, introducing "here" and "allot" words, and "c@" and "c!" for byte-wise loads and stores

25:54Spec out our dynamic dictionary entry definition implementation

27:48The "," helper word

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27:48The "," helper word

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27:48The "," helper word

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28:49Continue to spec out our dynamic dictionary entry definition implementation

35:15Introduce "swap" word

36:10Spec out a "cmove" word, as if we have all the facilities for it

43:11Introduce "rot" and "-rot" words

45:17Expand our cmove spec to FORTH

49:38Introduce branch

49:57sci4me Uh, that doesn't duplicate the top two elements, that duplicates the top element twice

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49:57sci4me Uh, that doesn't duplicate the top two elements, that duplicates the top element twice

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49:57sci4me Uh, that doesn't duplicate the top two elements, that duplicates the top element twice

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50:01Introduce "over" word

51:12Expand "2dup"

51:50rygorous pervognsen I'm gonna go out on a limb here and say you should write a small bootstrapping tool that converts those basic definitions into assembly, because transcribing that is gonna get old fast

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51:50rygorous pervognsen I'm gonna go out on a limb here and say you should write a small bootstrapping tool that converts those basic definitions into assembly, because transcribing that is gonna get old fast

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51:50rygorous pervognsen I'm gonna go out on a limb here and say you should write a small bootstrapping tool that converts those basic definitions into assembly, because transcribing that is gonna get old fast

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52:23Fix 2dup

52:57Expand "branch"

54:21Introduce "mux" for "branch" to use

59:11rygorous pervognsen x ^ ((y ^ x) & mask)

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59:11rygorous pervognsen x ^ ((y ^ x) & mask)

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59:11rygorous pervognsen x ^ ((y ^ x) & mask)

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59:49Move our newly defined words into the FORTH implementation

1:04:35Test mux

1:05:45Run it to see that the mux test fails

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1:05:45Run it to see that the mux test fails

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1:05:45Run it to see that the mux test fails

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1:06:04Remove the mux from our input_buf

1:06:08Run it to see 0 as expected

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1:06:08Run it to see 0 as expected

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1:06:08Run it to see 0 as expected

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1:06:16Reinsert mux into our input_buf, and endeavour to fix its definition, introducing a "neg" word

1:07:44Run it to see that it never prints anything

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1:07:44Run it to see that it never prints anything

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1:07:44Run it to see that it never prints anything

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1:09:18Fix the definitions of our new words as words, rather than codes

1:09:32Run it to see that it prints "0"

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1:09:32Run it to see that it prints "0"

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1:09:32Run it to see that it prints "0"

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1:09:38Re-enable some of the "mux" definition

1:09:44Run it to see that it prints "0"

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1:09:44Run it to see that it prints "0"

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1:09:44Run it to see that it prints "0"

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1:09:53Change our mux test to use 1

1:09:56Run it to see that it prints "/" in lieu of a -1

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1:09:56Run it to see that it prints "/" in lieu of a -1

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1:09:56Run it to see that it prints "/" in lieu of a -1

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1:10:21Change our mux test to use 4

1:10:25Run it to see that it prints "/" in lieu of a 4

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1:10:25Run it to see that it prints "/" in lieu of a 4

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1:10:25Run it to see that it prints "/" in lieu of a 4

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1:10:32Re-enable our entire "mux" definition

1:10:48Run it to see that it prints "0"

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1:10:48Run it to see that it prints "0"

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1:10:48Run it to see that it prints "0"

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1:11:10Flesh out of "mux" word spec, introducing "xor" and "not" words

1:13:43Run it to see that it prints "."

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1:13:43Run it to see that it prints "."

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1:13:43Run it to see that it prints "."

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1:13:52Scrutinise our "mux" definition, and consider the need for better debugging functionality

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1:13:52Scrutinise our "mux" definition, and consider the need for better debugging functionality

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1:13:52Scrutinise our "mux" definition, and consider the need for better debugging functionality

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1:16:25Fix "xor"

1:16:32Continue to scrutinise the words called by "mux"

1:17:33Break down our mux test

1:18:25Introduce "show" word, and enable cmd_loop() in the assembler to quit when "q" is pressed

1:21:57Run it, crash in step() and investigate why

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1:21:57Run it, crash in step() and investigate why

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1:21:57Run it, crash in step() and investigate why

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1:27:28Fix the uintptr_t definition in Ion

1:28:01Run it, successfully hit our breakpoint and inspect the workings of "mux"

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1:28:01Run it, successfully hit our breakpoint and inspect the workings of "mux"

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1:28:01Run it, successfully hit our breakpoint and inspect the workings of "mux"

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1:29:36Inline our mux definition

1:30:47Step through our FORTH program to find that the "<>0" didn't work

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1:30:47Step through our FORTH program to find that the "<>0" didn't work

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1:30:47Step through our FORTH program to find that the "<>0" didn't work

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1:32:47Fix "<>0" to "0<>" in our input stream

1:32:57Step through our FORTH program to find that the rotation is incorrect

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1:32:57Step through our FORTH program to find that the rotation is incorrect

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1:32:57Step through our FORTH program to find that the rotation is incorrect

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1:34:34Fix our "-rot" definition

1:34:39Step through our FORTH program to find that the entire routine works

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1:34:39Step through our FORTH program to find that the entire routine works

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1:34:39Step through our FORTH program to find that the entire routine works

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1:36:30Implement "branch"

1:37:26Test "branch" out on a toggle program

1:41:18Run it to see how it works

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1:41:18Run it to see how it works

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1:41:18Run it to see how it works

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1:41:39Make the program echo the input before doing the branch

1:41:54Run it to determine that the branching may be busted, and investigate why

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1:41:54Run it to determine that the branching may be busted, and investigate why

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1:41:54Run it to determine that the branching may be busted, and investigate why

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1:42:30Test to find that the infinite loop is indeed working

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1:42:30Test to find that the infinite loop is indeed working

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1:42:30Test to find that the infinite loop is indeed working

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1:42:50Scrutinise our "branch" definition

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1:42:50Scrutinise our "branch" definition

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1:42:50Scrutinise our "branch" definition

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1:45:32Make the program call "show" before and after branching

1:45:48Step in to our program and crash in bus_load_word()

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1:45:48Step in to our program and crash in bus_load_word()

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1:45:48Step in to our program and crash in bus_load_word()

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1:46:39Try a variant of "branch" that should unconditionally fall through

1:47:04Run it to find that it is unconditionally falling through

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1:47:04Run it to find that it is unconditionally falling through

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1:47:04Run it to find that it is unconditionally falling through

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1:47:23Try a variant of "branch" testing that the offset is correct

1:47:31Run it to confirm that the branch offset is correct

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1:47:31Run it to confirm that the branch offset is correct

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1:47:31Run it to confirm that the branch offset is correct

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1:48:00Fix "branch" to swap between add and load

1:49:10Run it to find that it works now

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1:49:10Run it to find that it works now

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1:49:10Run it to find that it works now

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1:50:07Implement "cmove" from our spec

1:55:16Determine to test our "cmove"

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1:55:16Determine to test our "cmove"

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1:55:16Determine to test our "cmove"

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1:55:53sci4me That's not quite right. You're storing to the wrong location, I think

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1:55:53sci4me That's not quite right. You're storing to the wrong location, I think

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1:55:53sci4me That's not quite right. You're storing to the wrong location, I think

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1:56:11Scrutinise our "cmove" spec

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1:56:11Scrutinise our "cmove" spec

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1:56:11Scrutinise our "cmove" spec

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1:57:24Loft out some of "cmove" into a "cmove1" word, introducing "1+" and "1-"

2:01:48Conjugation

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2:01:48Conjugation

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2:01:48Conjugation

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2:04:19miotatsu My introduction to conjugation as well as commutators was Rubik's cubes, fun stuff

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2:04:19miotatsu My introduction to conjugation as well as commutators was Rubik's cubes, fun stuff

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2:04:19miotatsu My introduction to conjugation as well as commutators was Rubik's cubes, fun stuff

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2:05:48Implement "create" from our spec

2:08:30Spec out "aligned" and "align"

2:09:59Implement "aligned" from our spec, and "2" and "3" literals

2:11:20Test "aligned" (also implementing "align" from our spec)

2:12:36Run it to see that it looks good

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2:12:36Run it to see that it looks good

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2:12:36Run it to see that it looks good

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2:13:33Break

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2:13:33Break

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2:13:33Break

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2:13:54afk

2:14:43Return and enable "create" to set the cfa field, introducing "docol"

2:16:53Introduce "'" word

2:18:44Test "create" on an "8" word, based on 4 × 2

2:22:34Step in to our program to see that the "create" has worked

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2:22:34Step in to our program to see that the "create" has worked

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2:22:34Step in to our program to see that the "create" has worked

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2:25:41Test "create" on a "twice" word

2:26:54Run it to find that it's not working, and investigate why

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2:26:54Run it to find that it's not working, and investigate why

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2:26:54Run it to find that it's not working, and investigate why

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2:29:57Assert that there is space on the stack for a new dictionary entry

2:33:14Investigate the stack effects of "create"

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2:33:14Investigate the stack effects of "create"

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2:33:14Investigate the stack effects of "create"

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2:35:23Make "cmove" drop its arguments, introducing "2drop" and "3drop"

2:36:39Step through it until we crash in bus_load_word()

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2:36:39Step through it until we crash in bus_load_word()

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2:36:39Step through it until we crash in bus_load_word()

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2:37:25Verify that multi-character definitions do not work

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2:37:25Verify that multi-character definitions do not work

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2:37:25Verify that multi-character definitions do not work

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2:37:53Try creating a 3-character dictionary entry

2:38:29Run it to determine that it could be an alignment or length issue

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2:38:29Run it to determine that it could be an alignment or length issue

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2:38:29Run it to determine that it could be an alignment or length issue

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2:40:11Scrutinise "cmove1", "cmove" and "create"

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2:40:11Scrutinise "cmove1", "cmove" and "create"

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2:40:11Scrutinise "cmove1", "cmove" and "create"

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2:41:56Cut off the stream

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2:41:56Cut off the stream

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2:41:56Cut off the stream

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