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3 changed files with 116 additions and 67 deletions

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@@ -49,24 +49,29 @@ listed in alphabetical order. Below in @if-table is a list of available IFs.
#figure(
table(
columns: (1fr, auto),
columns: (auto, auto, 1fr),
inset: 10pt,
align: center,
fill: (_, y) =>
if calc.odd(y) { luma(250) }
else { white },
table.header(
[*Name* (pg. no.)], [*Description*]
[*Name* (pg. no.)], [*Command Token*], [*Description*]
),
[`CALL` (#ref(<if-call>, form: "page"))],
[`$00`],
[Call a resident routine in the MPU's address space.],
[`HELP` (#ref(<if-help>, form: "page"))],
[`$01`],
[Display a summary of known commands.],
[`PEEK` (#ref(<if-peek>, form: "page"))],
[`$02`],
[Dumps memory from the MPU's address space to the terminal.],
[`POKE` (#ref(<if-poke>, form: "page"))],
[`$03`],
[Overwrites memory in the MPU's address space.],
[`SREC` (#ref(<if-srec>, form: "page"))],
[`$04`],
[Switches into Motorola S-Record receive mode.],
),
caption: [Table of IFs],
@@ -75,8 +80,7 @@ listed in alphabetical order. Below in @if-table is a list of available IFs.
In the following pages these IFs are described in specific.
IFs are tokenized from their textual form into a binary "bytecode" form. This
bytecode is not reliably stable between versions, so it isn't described here in
specific, but a general breakdown is provided.
bytecode is described in @internals.
First the text command name (eg. `CALL`) is hashed in some way into a token.
Then conditional processing on the remainder of the line occurs. Values given in
@@ -147,12 +151,12 @@ BIOS routine.
syntax: [`PEEK <BASE> [<HIGH>]`],
params: (
base: [
The address of the byte to dump or the base (lower bound) address of the
byte to start dumping from if `<HIGH>` is specified.
The address (two bytes) of the byte to dump or the base (lower bound)
address of the byte to start dumping from if `<HIGH>` is specified.
],
high: [
An optional operand given as the upper bound of the range to dump. Forms
a range together with `<BASE>`.
a range together with `<BASE>`. (two bytes)
],
)
)
@@ -160,8 +164,6 @@ BIOS routine.
Peeking memory causes the MPU to read the requested bytes and dump them to the
screen.
#lorem(120)
#pagebreak()
=== IF: `POKE` <if-poke>
@@ -170,12 +172,13 @@ screen.
desc: "Writes values to the MPU's address space.",
syntax: [`POKE <ADDR> <BYTES>`],
params: (
addr: "The base (low) address to start writing bytes from.",
addr: "The base (low) address (two bytes) to start writing bytes from.",
bytes: "The bytes to write into memory separated by whitespace.",
)
)
#lorem(120)
Poking memory causes the MPU to overwrite the bytes at `<ADDR>` with the bytes
given in `<BYTES>`.
#pagebreak()
@@ -187,7 +190,7 @@ screen.
params: (),
)
#lorem(120)
Motorola S-Record mode is currently a stub.
#pagebreak()
@@ -273,7 +276,9 @@ Building the documentation can also be accomplished using `make docs`, provided
= BUZBEE Internals and Modding <internals>
BUZBEE's interpreter works by "compiling" textual user commands into bytecode
for more simply passing parameters to IFs (see @if-top).
for more simply passing parameters to IFs (see @if-top). The way that works is
the implementation dependent, but each hash is one byte (1B) in size, and
corresponds to an IF token, which is the index of the hash.
BUZBEE's source, and the surrounding BIOS source is well commented, but a
general summary of the control flow is provided here.

View File

@@ -40,13 +40,13 @@ BBVAR tagbbvar
EXPORT BUZBEE
BUZBEE
lbsr NEWLINE ; Setup the new input line and handle display.
bsr INPLOOP ; Fill input buffer.
cmpy #$0000 ; No data?
beq BUZBEE ; Try again...
; TODO: Parse the input buffer into tokens
lbsr RUNIF
bra BUZBEE
lbsr NEWLINE ; Setup the new input line and handle display.
bsr INPLOOP ; Fill input buffer.
cmpy #0 ; No data?
beq BUZBEE ; Try again...
lbsr TOKENIZE ; Try to tokenize the input buffer
lbsr RUNIF ; Execute token buffer, handling any errors
bra BUZBEE ; Repeat
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
@@ -58,7 +58,7 @@ BUZBEE
; offset in the input buffer of the last char read.
INPLOOP
jsr PINCHAR ; Try to read a char
cmpd #$0000 ; If no char keep waitin'
cmpd #0 ; If no char keep waitin'
beq INPLOOP
bitb #UARTF_LSR_DR ; Is there a char in A?
beq NOCHAR@
@@ -101,7 +101,7 @@ HCR@
HESC@
lda #'^ ; Print a char that signifies that ESC was pressed
jsr POUTCHAR
ldy #$0000 ; On return we cmpy #$0000 and if eq then newline.
ldy #0 ; On return we cmpy #0 and if eq then newline
rts
HBACKSPC@
clrb ; Clear last char
@@ -118,13 +118,13 @@ NEWLINE
PZSTR PROMPTLINE ; Print prompt line
CLRIN ; Label to just clear input buffer without newline
clra ; Init A and X
ldx #$0000
ldx #0
NEXT@
sta BBVAR.input,x ; Clear input buffer
leax 1,x
cmpx #BBIN_DEPTH
blo NEXT@
ldy #$0000 ; Reset buffer fill pointer
ldy #0 ; Reset buffer fill pointer
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -143,24 +143,22 @@ PBYTE
asra
asra
asra
bsr NYB2HEX ; Print A
jsr POUTCHAR
tfr b,a ; Print B next
bsr NYB2HEX ; Print B
jsr POUTCHAR
puls b
rts
; Converts a nybble into a valid hex digit
; @param A: nybble to convert to a char
; @return A: resulting char
NYB2HEX
anda #$0F
ora #'0 ; Add "0"
cmpa #$3A ; ":" "9"+1
blo SKIP@
adca #6 ; Add offset to "A" in ascii
SKIP@
ora #'0 ; Add '0' to offset to digits
cmpa #$3A ; Hex? ':' '9'+1
blo SKIPA@
adca #6 ; Hex offset
SKIPA@
jsr POUTCHAR ; Print char in A
andb #$0F
orb #'0 ; Add '0' to offset to digits
cmpb #$3A ; Hex? ':' '9'+1
blo SKIPB@
adcb #6 ; Hex offset
SKIPB@
tfr b,a ; Print char in B
jsr POUTCHAR
puls b ; Restore B
rts
; Converts a hexadecimal sequence into a byte value
@@ -203,19 +201,77 @@ BADHEX@
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Attempts to parse the input buffer into tokens depending on the command
TOKENIZE
ldd BBVAR.cchinput ; Do we have input to work with?
cmpd #4 ; Do we have even enough space for a string command
blo TOKFAIL@ ; No? GTFO
ldy #0 ; Initialize Y; used to track current position in BBVAR.input
ldx #0 ; Initialize X; used to track position in BBVAR.tokens
bsr SKIPTONEXTC ; Get the next non-whitespace char
bsr MKCMDSUM ; Hash the first four non-whitespace chars
bsr HASH2TOKEN ; Try to turn that hash into a proper token
bcs TOKFAIL@
bra STTOK@ ; Store token
NEXTHEX@ ; Next hex token
bsr SKIPTONEXTC ; Skip to next whitespace
ldd BBVAR.input,y ; Get hex value (two digits)
bsr HEX2BYT ; Convert hex value to byte value
STTOK@
sta BBVAR.tokens,x ; Store curent token
leax 1,x ; Advance to next token
cmpx #BBTOKENS_DEPTH ; Is this next token in bounds?
beq FULLBUF@ ; No? handle a full buffer
bra NEXTHEX@ ; Try to turn the next character into a hex value
FULLBUF@
PZSTR EM_FULLTOKBUF ; Print an error message
clrd ; Say we wrote no tokens
std BBVAR.cbtokens
rts
TOKFAIL@
PZSTR EM_TOKFAIL ; Print tokenization fail
clrd ; Say we wrote no tokens
std BBVAR.cbtokens
rts
; Converts a runtime command hash into a portable token. Command tokens are
; indexes into BBCHT, which is generated at compile-time
; @param A: runtime hash
; @return A: output token
; @return CC.C: set if error state, cleared otherwise
HASH2TOKEN
pshs x ; Preserve & init X; other routines in this group use it
ldx #0
NEXTHASH@
cmpa BBCHT,x ; Is this hash our hash?
beq THISHASH@ ; Yes? turn it into a token
leax 1,x ; Begin considering next hash
cmpx BBCHTC ; Is the next hash even in the table?
blo NEXTHASH@ ; Yes? try this next hash, No? fall through
PZSTR EM_BADHASH CALL; Print an error message to the user
puls x
orcc #1 ; Set CC.C to indicate error
rts
THISHASH@
puls x
andcc #$FE ; Clear CC.C to indicate success
rts
; Makes a hash of four chars in BBIN starting at offset X
; @param X: offset in BBIN to read the four chars from
; @param Y: offset in BBIN to read the four chars from
; @return A: resulting hash
; @return Y: offset after hash processing
MKCMDSUM
pshs b
ldb #4 ; Loop over four chars
clra ; Initialize accumulator
NEXTC@
suba BBVAR.input,x ; Subtract current char from accumulator
leax 1,x ; Next char
suba BBVAR.input,y ; Subtract current char from accumulator
leax 1,y ; Next char
decb ; Reduce count
cmpb #0 ; Are we at the end?
bne NEXTC@ ; No? loop
puls b
rts
; Skips "whitespace" to the next semantic char
@@ -245,24 +301,15 @@ RUNIF
beq NOTOK@
ldx #0 ; Counting up from zero
lda BBVAR.tokens ; Load token
NEXTHASH@
cmpa BBCHT,x ; Is this hash our hash?
beq CALCPTR@ ; Yes? skip to next step to put ptr in x
leax 1,x ; Begin considering next hash
cmpx BBCHTC ; Is this the last byte?
blo NEXTHASH@ ; No? try next hash, Yes? fall through
PZSTR EM_BADHASH ; Print an error message
lbra IFHELP ; Proceed to call "HELP"
CALCPTR@
tfr x,d ; Swap into d to do a cheap multiply
tfr a,b ; Get the index in D
asld ; Cheaply << to get *2, pointer size
tfr d,x ; Restore x from d and jump to function at index
jmp [BBCMDPTRTBL,x]
tfr d,x ; Move to X so we can use indexed mode with the offset
jmp [IFPTRTBL,x] ; Select IF
NOTOK@
rts
; IF pointer table
BBCMDPTRTBL
IFPTRTBL
fdb IFCALL
fdb IFHELP
fdb IFPEEK
@@ -388,5 +435,8 @@ EM_TOKFAIL
fcc "!!! Tokenization Failure !!!"
fcb $0D,$0A,$00
EM_BADHEX
fcc "!!! Maleformed Hex Value !!!"
fcc "!!! Malformed Hex Value !!!"
fcb $0D,$0A,$00
EM_FULLTOKBUF
fcc "!!! Token Buffer Overrun !!!"
fcb $0D,$0A,$00

View File

@@ -24,7 +24,7 @@ RESET
CLRSTACK
; Initialize the system stack
clra ; Init A & X to zero out the stack
ldx #$0000
ldx #0
NEXT@
sta STACK_BOTTOM,x ; Write a zero and progress to the next byte
leax 1,x
@@ -36,18 +36,12 @@ BOOTSCR
lda #13 ; 9600 baud
ldb #%11 ; 8N1
jsr INITUART ; Initialize serial console
ldx #VERMSG ; Print version information
jsr POUTZSTR
; Progress to POST
POST
jsr RAMTEST
PZSTR VERMSG ; Print version information
; Hand off control to the BUZBEE monitor and print notification of leaving the
; firmware
ENTERMON
ldx #TXTRUN
jsr POUTZSTR
PZSTR TXTRUN
jmp BUZBEE
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;