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f68fa4c0a6
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d92b8f6ba4
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96a5804467
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9ab92eb8a5
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a6a93e656a
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b5cfd501c5
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@@ -49,24 +49,29 @@ listed in alphabetical order. Below in @if-table is a list of available IFs.
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#figure(
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table(
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columns: (1fr, auto),
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columns: (auto, auto, 1fr),
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inset: 10pt,
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align: center,
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fill: (_, y) =>
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if calc.odd(y) { luma(250) }
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else { white },
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table.header(
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[*Name* (pg. no.)], [*Description*]
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[*Name* (pg. no.)], [*Command Token*], [*Description*]
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),
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[`CALL` (#ref(<if-call>, form: "page"))],
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[`$00`],
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[Call a resident routine in the MPU's address space.],
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[`HELP` (#ref(<if-help>, form: "page"))],
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[`$01`],
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[Display a summary of known commands.],
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[`PEEK` (#ref(<if-peek>, form: "page"))],
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[`$02`],
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[Dumps memory from the MPU's address space to the terminal.],
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[`POKE` (#ref(<if-poke>, form: "page"))],
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[`$03`],
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[Overwrites memory in the MPU's address space.],
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[`SREC` (#ref(<if-srec>, form: "page"))],
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[`$04`],
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[Switches into Motorola S-Record receive mode.],
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),
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caption: [Table of IFs],
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@@ -75,8 +80,7 @@ listed in alphabetical order. Below in @if-table is a list of available IFs.
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In the following pages these IFs are described in specific.
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IFs are tokenized from their textual form into a binary "bytecode" form. This
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bytecode is not reliably stable between versions, so it isn't described here in
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specific, but a general breakdown is provided.
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bytecode is described in @internals.
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First the text command name (eg. `CALL`) is hashed in some way into a token.
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Then conditional processing on the remainder of the line occurs. Values given in
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@@ -147,12 +151,12 @@ BIOS routine.
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syntax: [`PEEK <BASE> [<HIGH>]`],
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params: (
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base: [
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The address of the byte to dump or the base (lower bound) address of the
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byte to start dumping from if `<HIGH>` is specified.
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The address (two bytes) of the byte to dump or the base (lower bound)
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address of the byte to start dumping from if `<HIGH>` is specified.
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],
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high: [
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An optional operand given as the upper bound of the range to dump. Forms
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a range together with `<BASE>`.
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a range together with `<BASE>`. (two bytes)
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],
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)
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)
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@@ -160,8 +164,6 @@ BIOS routine.
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Peeking memory causes the MPU to read the requested bytes and dump them to the
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screen.
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#lorem(120)
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#pagebreak()
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=== IF: `POKE` <if-poke>
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@@ -170,12 +172,13 @@ screen.
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desc: "Writes values to the MPU's address space.",
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syntax: [`POKE <ADDR> <BYTES>`],
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params: (
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addr: "The base (low) address to start writing bytes from.",
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addr: "The base (low) address (two bytes) to start writing bytes from.",
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bytes: "The bytes to write into memory separated by whitespace.",
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)
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)
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#lorem(120)
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Poking memory causes the MPU to overwrite the bytes at `<ADDR>` with the bytes
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given in `<BYTES>`.
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#pagebreak()
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@@ -187,7 +190,7 @@ screen.
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params: (),
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)
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#lorem(120)
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Motorola S-Record mode is currently a stub.
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#pagebreak()
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@@ -273,7 +276,9 @@ Building the documentation can also be accomplished using `make docs`, provided
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= BUZBEE Internals and Modding <internals>
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BUZBEE's interpreter works by "compiling" textual user commands into bytecode
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for more simply passing parameters to IFs (see @if-top).
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for more simply passing parameters to IFs (see @if-top). The way that works is
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the implementation dependent, but each hash is one byte (1B) in size, and
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corresponds to an IF token, which is the index of the hash.
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BUZBEE's source, and the surrounding BIOS source is well commented, but a
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general summary of the control flow is provided here.
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140
src/buzbee.s
140
src/buzbee.s
@@ -40,13 +40,13 @@ BBVAR tagbbvar
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EXPORT BUZBEE
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BUZBEE
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lbsr NEWLINE ; Setup the new input line and handle display.
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bsr INPLOOP ; Fill input buffer.
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cmpy #$0000 ; No data?
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beq BUZBEE ; Try again...
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; TODO: Parse the input buffer into tokens
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lbsr RUNIF
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bra BUZBEE
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lbsr NEWLINE ; Setup the new input line and handle display.
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bsr INPLOOP ; Fill input buffer.
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cmpy #0 ; No data?
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beq BUZBEE ; Try again...
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lbsr TOKENIZE ; Try to tokenize the input buffer
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lbsr RUNIF ; Execute token buffer, handling any errors
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bra BUZBEE ; Repeat
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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@@ -58,7 +58,7 @@ BUZBEE
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; offset in the input buffer of the last char read.
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INPLOOP
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jsr PINCHAR ; Try to read a char
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cmpd #$0000 ; If no char keep waitin'
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cmpd #0 ; If no char keep waitin'
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beq INPLOOP
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bitb #UARTF_LSR_DR ; Is there a char in A?
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beq NOCHAR@
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@@ -101,7 +101,7 @@ HCR@
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HESC@
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lda #'^ ; Print a char that signifies that ESC was pressed
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jsr POUTCHAR
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ldy #$0000 ; On return we cmpy #$0000 and if eq then newline.
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ldy #0 ; On return we cmpy #0 and if eq then newline
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rts
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HBACKSPC@
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clrb ; Clear last char
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@@ -118,13 +118,13 @@ NEWLINE
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PZSTR PROMPTLINE ; Print prompt line
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CLRIN ; Label to just clear input buffer without newline
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clra ; Init A and X
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ldx #$0000
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ldx #0
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NEXT@
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sta BBVAR.input,x ; Clear input buffer
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leax 1,x
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cmpx #BBIN_DEPTH
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blo NEXT@
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ldy #$0000 ; Reset buffer fill pointer
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ldy #0 ; Reset buffer fill pointer
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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@@ -143,24 +143,22 @@ PBYTE
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asra
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asra
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asra
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bsr NYB2HEX ; Print A
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jsr POUTCHAR
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tfr b,a ; Print B next
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bsr NYB2HEX ; Print B
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jsr POUTCHAR
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puls b
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rts
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; Converts a nybble into a valid hex digit
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; @param A: nybble to convert to a char
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; @return A: resulting char
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NYB2HEX
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anda #$0F
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ora #'0 ; Add "0"
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cmpa #$3A ; ":" "9"+1
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blo SKIP@
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adca #6 ; Add offset to "A" in ascii
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SKIP@
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ora #'0 ; Add '0' to offset to digits
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cmpa #$3A ; Hex? ':' '9'+1
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blo SKIPA@
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adca #6 ; Hex offset
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SKIPA@
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jsr POUTCHAR ; Print char in A
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andb #$0F
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orb #'0 ; Add '0' to offset to digits
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cmpb #$3A ; Hex? ':' '9'+1
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blo SKIPB@
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adcb #6 ; Hex offset
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SKIPB@
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tfr b,a ; Print char in B
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jsr POUTCHAR
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puls b ; Restore B
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rts
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; Converts a hexadecimal sequence into a byte value
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@@ -203,19 +201,77 @@ BADHEX@
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Attempts to parse the input buffer into tokens depending on the command
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TOKENIZE
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ldd BBVAR.cchinput ; Do we have input to work with?
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cmpd #4 ; Do we have even enough space for a string command
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blo TOKFAIL@ ; No? GTFO
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ldy #0 ; Initialize Y; used to track current position in BBVAR.input
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ldx #0 ; Initialize X; used to track position in BBVAR.tokens
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bsr SKIPTONEXTC ; Get the next non-whitespace char
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bsr MKCMDSUM ; Hash the first four non-whitespace chars
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bsr HASH2TOKEN ; Try to turn that hash into a proper token
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bcs TOKFAIL@
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bra STTOK@ ; Store token
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NEXTHEX@ ; Next hex token
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bsr SKIPTONEXTC ; Skip to next whitespace
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ldd BBVAR.input,y ; Get hex value (two digits)
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bsr HEX2BYT ; Convert hex value to byte value
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STTOK@
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sta BBVAR.tokens,x ; Store curent token
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leax 1,x ; Advance to next token
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cmpx #BBTOKENS_DEPTH ; Is this next token in bounds?
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beq FULLBUF@ ; No? handle a full buffer
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bra NEXTHEX@ ; Try to turn the next character into a hex value
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FULLBUF@
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PZSTR EM_FULLTOKBUF ; Print an error message
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clrd ; Say we wrote no tokens
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std BBVAR.cbtokens
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rts
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TOKFAIL@
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PZSTR EM_TOKFAIL ; Print tokenization fail
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clrd ; Say we wrote no tokens
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std BBVAR.cbtokens
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rts
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; Converts a runtime command hash into a portable token. Command tokens are
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; indexes into BBCHT, which is generated at compile-time
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; @param A: runtime hash
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; @return A: output token
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; @return CC.C: set if error state, cleared otherwise
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HASH2TOKEN
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pshs x ; Preserve & init X; other routines in this group use it
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ldx #0
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NEXTHASH@
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cmpa BBCHT,x ; Is this hash our hash?
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beq THISHASH@ ; Yes? turn it into a token
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leax 1,x ; Begin considering next hash
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cmpx BBCHTC ; Is the next hash even in the table?
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blo NEXTHASH@ ; Yes? try this next hash, No? fall through
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PZSTR EM_BADHASH CALL; Print an error message to the user
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puls x
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orcc #1 ; Set CC.C to indicate error
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rts
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THISHASH@
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puls x
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andcc #$FE ; Clear CC.C to indicate success
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rts
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; Makes a hash of four chars in BBIN starting at offset X
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; @param X: offset in BBIN to read the four chars from
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; @param Y: offset in BBIN to read the four chars from
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; @return A: resulting hash
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; @return Y: offset after hash processing
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MKCMDSUM
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pshs b
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ldb #4 ; Loop over four chars
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clra ; Initialize accumulator
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NEXTC@
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suba BBVAR.input,x ; Subtract current char from accumulator
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leax 1,x ; Next char
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suba BBVAR.input,y ; Subtract current char from accumulator
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leax 1,y ; Next char
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decb ; Reduce count
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cmpb #0 ; Are we at the end?
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bne NEXTC@ ; No? loop
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puls b
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rts
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; Skips "whitespace" to the next semantic char
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@@ -245,24 +301,15 @@ RUNIF
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beq NOTOK@
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ldx #0 ; Counting up from zero
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lda BBVAR.tokens ; Load token
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NEXTHASH@
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cmpa BBCHT,x ; Is this hash our hash?
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beq CALCPTR@ ; Yes? skip to next step to put ptr in x
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leax 1,x ; Begin considering next hash
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cmpx BBCHTC ; Is this the last byte?
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blo NEXTHASH@ ; No? try next hash, Yes? fall through
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PZSTR EM_BADHASH ; Print an error message
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lbra IFHELP ; Proceed to call "HELP"
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CALCPTR@
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tfr x,d ; Swap into d to do a cheap multiply
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tfr a,b ; Get the index in D
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asld ; Cheaply << to get *2, pointer size
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tfr d,x ; Restore x from d and jump to function at index
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jmp [BBCMDPTRTBL,x]
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tfr d,x ; Move to X so we can use indexed mode with the offset
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jmp [IFPTRTBL,x] ; Select IF
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NOTOK@
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rts
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; IF pointer table
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BBCMDPTRTBL
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IFPTRTBL
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fdb IFCALL
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fdb IFHELP
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fdb IFPEEK
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@@ -388,5 +435,8 @@ EM_TOKFAIL
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fcc "!!! Tokenization Failure !!!"
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fcb $0D,$0A,$00
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EM_BADHEX
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fcc "!!! Maleformed Hex Value !!!"
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fcc "!!! Malformed Hex Value !!!"
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fcb $0D,$0A,$00
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EM_FULLTOKBUF
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fcc "!!! Token Buffer Overrun !!!"
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fcb $0D,$0A,$00
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12
src/reset.s
12
src/reset.s
@@ -24,7 +24,7 @@ RESET
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CLRSTACK
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; Initialize the system stack
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clra ; Init A & X to zero out the stack
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ldx #$0000
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ldx #0
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NEXT@
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sta STACK_BOTTOM,x ; Write a zero and progress to the next byte
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leax 1,x
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@@ -36,18 +36,12 @@ BOOTSCR
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lda #13 ; 9600 baud
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ldb #%11 ; 8N1
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jsr INITUART ; Initialize serial console
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ldx #VERMSG ; Print version information
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jsr POUTZSTR
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; Progress to POST
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POST
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jsr RAMTEST
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PZSTR VERMSG ; Print version information
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; Hand off control to the BUZBEE monitor and print notification of leaving the
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; firmware
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ENTERMON
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ldx #TXTRUN
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jsr POUTZSTR
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PZSTR TXTRUN
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jmp BUZBEE
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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Reference in New Issue
Block a user