Makefile

@@ -20,7 +20,6 @@ $(BUILD_DIR):
 	mkdir $@
 
 .PHONY: default test clean
-.DEFAULT_GOAL 	= default
 default: $(ROM)
 test: ../test.bin
 

details.md

@@ -1,19 +1,13 @@
 # Project details
 ## Address Space
-|Name|From|To|r/w|
+### RAM: $0-$7fff 
-|---|---:|---:|:---:|
+### (EEP)ROM: $8000-$ffff
-|ZEROPAGE   |$00    |$ff    |`rw`|
-|STACK      |$100   |$1ff   |`rw`|
-|RAM        |$200   |$4fff  |`rw`|
-|SPI        |$5000  |$5fff  |`rw`|
-|VIA1       |$6000  |$600f  |`rw`|
-|VIA2       |$7000  |$700f  |`rw`|
-|ROM        |$8000  |$ffff  |`r `|
 
 ## Naming conventions
 leading underscors `_` indicate a "private" label/variable, that is meant for internal use within the module only.
 ### Labels
-- **scopes**: snake case 
+- `namespace_fname` for exported subroutines
-- **subroutines** and **variables**: snake case (`scope::(_)fname_snake_case` or `scope::(_)varname_2`)
+- `_namespace_fname` or `_namespace_fname_sub` for internal labels
-- **macros**: camel case (`(_)GoodMacroname`)
+- `(_)namespace_Macroname`
-- **constants** (eg. in ROM): upper case (`scope::(_)NICE_SYMBOLNAME`)
+- `(_)NAMESPACE_SYMBOLNAME` for constant symbols
+- `(_)NAMESPACE_symbolname` for variables

main.s65

@@ -2,7 +2,6 @@
 .code
 
 .macro DEBUG_LED_OFF nr
-    pha
     lda IO1 + IO::RA
 .if nr = 0
     and #%11111110
@@ -10,11 +9,9 @@
     and #%11111101
 .endif
     sta IO1 + IO::RA
-    pla
 .endmacro
 
 .macro DEBUG_LED_ON nr
-    pha
     lda IO1 + IO::RA
 .if nr = 0
     ora #%00000001
@@ -22,7 +19,6 @@
     ora #%00000010
 .endif
     sta IO1 + IO::RA
-    pla
 .endmacro
 
 ;********************************************************************************    
@@ -41,7 +37,6 @@ SPI_IO = IO2
 ; Printer
     .include "programs/printer.s65"
     .include "programs/print_slow.s65"
-    .include "programs/spi-menu.s65"
 ; Digital Humidity and Temerature Sensor
     ; .include "dht.s65"
 
@@ -66,8 +61,8 @@ irq:
     lda IO2+IO::IFR
     sta IRQ_VAR
     bbr7 IRQ_VAR,@irq_return
+    bbs1 IRQ_VAR,@irq_keypad  ; check CB1
     bbs2 IRQ_VAR,@irq_spi_p  ; check SR
-    bbs1 IRQ_VAR,@irq_keypad  ; check CA1
     ; this should never be reached
     jsr lcd_clear
     Print str_irq_unknown
@@ -80,7 +75,7 @@ irq:
     jsr kp_read_on_irq
     bra @irq_return
 @irq_spi_p:
-    jsr spi_p::read
+    jsr spi_p_read
     bra @irq_return
 ; @irq_dht:
 ;     lda IO1 + IO::T1CL ;T1L2  ; clear interrupt flag
@@ -94,16 +89,15 @@ irq:
 reset:
     jsr lcd_init
 
-    ; TODO debug stuff
-    stz IO2 + IO::DDRB
     lda #$ff
     sta IO1 + IO::DDRA
     DEBUG_LED_OFF 0
     DEBUG_LED_OFF 1
 
-
     jsr kp_init
 
+    jsr spi_p_init
+
 
     ; ; INIT DHT
     ; lda #%11000010  ; enable interrupt for Timer 1 and CA1 on IO2
@@ -118,61 +112,48 @@ reset:
 
     ; enable interrupts
     cli
-    bra home
+ 
+.proc return_home
+    Print message_menu
+.endproc
 
 .proc home
-    Print message_menu
+    jsr rb_keypad_read
-    ; jsr rb_keypad_read
+    beq home
-@loop:
-    lda _KP_DEBUG_VAL
-    beq @loop
-    ; TODO debug
-    sta 0
-    stz _KP_DEBUG_VAL
-    lda 0
     ; beq home
     cmp #'A'
     jeq printer
     cmp #'B'
-    jeq spi_menu::spi_menu
+    jeq SPI_CODE_START
+    ; jeq dht_request
     cmp #'C'
     jeq print_1
     cmp #'D'
     jeq print_2
-    cmp #'1'
+    cmp #'0'
-    beq @debug0_on
+    bne @l1
-    cmp #'2'
-    beq @debug0_off
-    cmp #'4'
-    beq @debug1_on
-    cmp #'5'
-    beq @debug1_off
-    cmp #'7'
-    beq @print_rb
-    cmp #'*'  ; print home menu again if not visible (message 1 and 2 jmp to home)
-    beq home
-    jmp @loop
-    
-@debug0_off:
     DEBUG_LED_OFF 0
-    jmp @loop
+    jmp home
-@debug0_on:
+@l1:
+    cmp #'#'
+    bne @l2
     DEBUG_LED_ON 0
-    jmp @loop
+    jmp home
-@debug1_off:
+@l2:
+    cmp #'8'
+    bne @l3
     DEBUG_LED_OFF 1
-    jmp @loop
+    jmp home
-@debug1_on:
+@l3:
+    cmp #'9'
+    bne @l4
     DEBUG_LED_ON 1
-    jmp @loop
+    jmp home
-@print_rb:
+@l4:
-    jsr lcd_clear
+    cmp #'*'  ; print home menu again if not visible (message 1 and 2 jmp to home)
-    Print str_io2
+    jeq return_home
-    lda IO2 + IO::RB
+
-    jsr lcd_char
+    jmp home
-    lda #'''
-    jsr lcd_char
-    jmp @loop
 .endproc
 
 
@@ -200,19 +181,13 @@ message_2:
 message_menu: 
     .byte   "<A> Printer     "
     ; .byte   "<B> Temperatur  "
-    .byte   "<B> SPI-Menu    "
+    .byte   "<B> Run from SPI"
     .byte   "<C> Text 1      "
     .asciiz "<D> Text 2      "
-str_spi_begin:
-    .asciiz "---BEGIN  SPI---"
-str_spi_start:
-    .asciiz "---START  SPI---"
 str_irq:
     .asciiz "IRQ detected!   "
 str_irq_unknown:
     .asciiz "Unknown IRQ src!"
-str_io2:
-    .asciiz "IO2::RB='"
 
 ;********************************************************************************
 ; reset vector

programs/memcopy.s65

@@ -12,8 +12,8 @@ INCLUDE_MEMCOPY = 1
     cpy
 loop:
     beq @loop_end
-    lda (ARG0),y
+    lda (ARG0,y)
-    sta (ARG2),y
+    sta (ARG2,y)
     dey
     bra @loop
 loop_end:

programs/print_slow.s65

@@ -33,9 +33,9 @@ INCLUDE_PRINT_SLOW = 1
 ;********************************************************************************
 .macro PrintSlow message,time_cs
     jsr lcd_clear
-    lda #<message
+    lda #.LOBYTE(message)
     sta ARG0
-    lda #>message
+    lda #.HIBYTE(message)
     sta ARG1
     phx
     ldx #time_cs

programs/printer.s65

@@ -10,7 +10,7 @@ printer:
     jsr rb_keypad_read
     beq @printer_loop
     cmp #'*'
-    jeq home
+    jeq return_home
     jsr lcd_char
     bra @printer_loop
 .endif  ; guard

programs/spi-menu.s65

@@ -1,92 +0,0 @@
-.include "system/spi.s65"
-.include "util/string.s65"
-.ifndef INCLUDE_SPI_MENU
-INCLUDE_SPI_MENU = 1
-
-.scope spi_menu
-.bss
-trans_bytes: .res 1
-trans_pages: .res 1
-status:      .res 1
-status_str:  .res 17  ; 16 + null
-
-.code
-.proc spi_menu
-    stz trans_bytes
-    stz trans_pages
-    lda #'X'
-    sta status
-@print_menu:
-    jsr lcd_clear
-    Print MENU
-@print_status:
-    Strf FMT_STATUS,status_str,trans_pages,trans_bytes,status
-    lda #(LCD_CMD_SET_ADDRESS | LCD_LINE4)
-    jsr _lcd_cmd
-    Print status_str
-@loop:
-    ; check if a byte has been transferred
-@check_byte:
-    lda spi_p::bytes_written
-    cmp trans_bytes
-    bne @byte_written
-@check_page:
-    lda spi_p::pages_written
-    cmp trans_pages
-    bne @page_written
-    bra @read_keypad
-@byte_written:
-    sta trans_bytes
-    bra @print_status
-@page_written:
-    sta trans_pages
-    bra @print_status
-
-@read_keypad:
-    lda _KP_DEBUG_VAL
-    beq @loop
-    ; TODO debug
-    sta 0
-    stz _KP_DEBUG_VAL
-    lda 0
-    cmp #'*'
-    beq @return_home
-    cmp #'A'
-    beq @spi_begin
-    cmp #'B'
-    beq @spi_end
-    cmp #'C'
-    beq @spi_jump
-    bra @loop
-@spi_begin:
-    lda #'@'
-    sta status
-    jsr spi_p::begin
-    jmp @print_menu
-@spi_end:
-    lda #'X'
-    sta status
-    jsr spi_p::end
-    jmp @print_menu
-@spi_jump:
-    jsr spi_p::end
-    jsr lcd_clear
-    Print START
-    jmp spi_p::SPI_CODE_START
-@return_home:
-    jsr spi_p::end
-    jmp home
-.endproc
-
-.rodata 
-MENU:
-    .byte   "A> Beg. Transfer"
-    .byte   "B> Stop Transfer"
-    .asciiz "C> Jump  Home <*"
-    ; .asciiz "0b0p   Status: X"
-FMT_STATUS: .asciiz "%x%xb  Status:%x"
-BEGIN:      .asciiz "---BEGIN  SPI---"
-START:      .asciiz "---START  SPI---"
-
-.endscope
-.endif  ; guard

system/io_W65C22.h65

@@ -102,5 +102,25 @@ INCLUDE_IOW65C22 = 1
     IRQ  = %10000000
 .endenum
 
-.endscope ; IO
+    ; TODO: leave?
-.endif  ; guard
+    ; .struct VIA_Pins
+    ;     RB   .byte   ; $0
+    ;     RA   .byte   ; $1
+    ;     DDRB .byte   ; $2
+    ;     DDRA .byte   ; $3
+    ;     T1CL .byte   ; $4
+    ;     T1CH .byte   ; $5
+    ;     T1LL .byte   ; $6
+    ;     T1LH .byte   ; $7
+    ;     T2CL .byte   ; $8
+    ;     T2CH .byte   ; $9
+    ;     SR   .byte   ; $a
+    ;     ACR  .byte   ; $b
+    ;     PCR  .byte   ; $c
+    ;     IFR  .byte   ; $d
+    ;     IER  .byte   ; $e
+    ;     RANH .byte   ; $f  ; no handshake
+    ; .endstruct
+.endif
+.endscope
+

system/keypad.s65

@@ -18,7 +18,6 @@ INCLUDE_KEYPAD = 1
 
 .zeropage
 _KP_COLUMN:         .res 1  ; for storing stuff
-_KP_DEBUG_VAL:      .res 1  ; for storing the last char DEBUG
 
 .bss  ; reserve space or ringbuffer
 KP_BUF_SIZE = 10
@@ -91,8 +90,6 @@ RBUF_MEM_END = RBUF_MEM_START + KP_BUF_SIZE - 1
     rts
 @kp_write:
     lda _KP_VALUES,x
-    ; TODO use ringbuffer
-    sta _KP_DEBUG_VAL
     jsr rb_keypad_write
     rts
 .endproc
@@ -100,9 +97,9 @@ RBUF_MEM_END = RBUF_MEM_START + KP_BUF_SIZE - 1
 .rodata
 _KP_VALUES:
     .byte "174*"
-    .byte "2850"
     .byte "396#"
-    .byte "ACBD"
+    .byte "2850"
+    .byte "ABCD"
     ; keypad conencted so that 
     ; row 1 = PA0
     ; row 2 = PA2

system/spi.s65

@@ -10,148 +10,30 @@
 
 .ifndef INCLUDE_SPI
 INCLUDE_SPI = 1
-.scope spi_p
 
 
-.zeropage
-code_page:          .res 2  ; SPI_CODE_START + pages_written * 256
 .bss
-bytes_written:      .res 1
+SPI_PAGES_WRITTEN:  .res 1
-pages_written:      .res 1
+SPI_BYTES_WRITTEN:  .res 1
-
-.include "util/math.s65"
-; spi-transferred code will be placed here
 .segment "SPI"
-SPI_CODE_START:
+SPI_CODE_START:     ; .res $1000
-    lda '$'
+    lda $1000
-    jsr lcd_char
+    sta $1000
-    lda #<TEST_FMT
+    lda $1000
-    sta ARG0
+    sta $1000
-    lda #>TEST_FMT
+    lda $1000
-    sta ARG1
+    sta $1000
-    lda #<TEST_OUT
-    sta ARG2
-    lda #>TEST_OUT
-    sta ARG3
-    lda #$a9
-    sta ARG4
-    lda #$3c
-    sta ARG5
-    lda #$10
-    sta ARG6
-    jsr strf
-    Print TEST_OUT
-@spiloop:
     lda IO1 + IO::RA
-    lda IO2 + IO::RA
+    lda IO1 + IO::RA
-    nop
+    bra SPI_CODE_START
-    bra @spiloop
+    ; jsr lcd_clear
-    jmp home
+    ; PrintSlow msg,20
-
+    ; jmp home
-; TODO allocate zp memory
+; msg:
-fmt_idx = $30
+    ; .asciiz "YO DAS WAR    SPI"
-out_idx = $31
-;********************************************************************************
-; @function Format a string
-; @details
-;   If there is no value to be read, the Pz will be set
-;   Formats:
-;   - u: unsigned decimal integer (1 byte)
-;   - U: unsigned decimal integer (2 bytes)
-; @param ARG0-1: Format string address
-; @param ARG2-3: Output string address
-; @param ARG4+:  Additional parameters
-; @returns 
-; @modifies: A, Y
-;********************************************************************************
-.proc strf
-    stz out_idx
-    stz fmt_idx
-    ldy #0  ; position in string
-    ldx #0  ; index of format args
-@loop:
-    ldy fmt_idx
-    lda (ARG0),y
-    beq @null
-    cmp #'%'
-    beq @percent
-@normal_char:  ; store A in output string
-        ldy out_idx
-        sta (ARG2),y
-        inc fmt_idx
-        inc out_idx
-        beq @out_overflow
-        bra @loop
-@percent:  ; check for format in next position
-        iny
-        sty fmt_idx
-        lda (ARG0),y
-        beq @null
-        ; formats
-        cmp #'x'
-        beq @format_hex1
-        bra @normal_char
-@format_hex1:   ; 1 byte hex -> 2 chars
-            lda ARG4,x
-            phx
-            jsr int8_to_hex_str
-            ldy out_idx
-            sta (ARG2),y  ; most sig digit
-            iny
-            beq @out_overflow
-            txa
-            sta (ARG2),y  ; least sig digit
-            iny
-            beq @out_overflow
-            sty out_idx
-            plx
-            inx  ; 1 byte of args handeled
-            ; bra @format_return
-@format_return:  ; increment fmt_idx to swallow the formating char
-        inc fmt_idx
-        bra @loop
-@out_overflow:  ; store 0 in last position
-    ldy #$ff
-    sty out_idx
-@store_null:
-    lda #0
-@null:  ; store and return
-    ldy out_idx
-    sta (ARG2),y
-@rts:
-    rts
-.endproc
-
-
-;********************************************************************************
-; @function Convert a 1 byte number into two hex characters
-; @param A: Number to convert
-; @returns A: Most significant digit
-; @returns X: Least significant digit
-; @modifies X,Y,A
-;********************************************************************************
-.proc int8_to_hex_str
-    pha
-    and #%00001111
-    tay
-    ldx HEX_CHARS,y
-    pla
-    div A,16
-    and #%00001111
-    tay
-    lda HEX_CHARS,y
-    rts
-.endproc
 
 
 
-
-HEX_CHARS: .byte "0123456789ABCDEF"
-
-TEST_FMT: .asciiz "%x -> %x -> %x:)"
-TEST_OUT: .asciiz "TESTOUT"
-
-; SPI_P = as peripheral
 .code
 .struct SPI_P_Pins
     ; VIA addresses
@@ -168,20 +50,12 @@ TEST_OUT: .asciiz "TESTOUT"
 .endstruct
 
 ;********************************************************************************
-; @function Begin listening for SPI transfers
+; @function Initialize the IO Adapter for SPI
-; @details
+; @param ARG0-1 Address of the SPI_Pins struct
-;   - initialize variables
-;   - configure shift register to shift in under external clock
-;   - enable shift register interrupts 
 ;********************************************************************************
-.proc begin
+.proc spi_p_init
-    stz pages_written
+    stz SPI_PAGES_WRITTEN
-    stz bytes_written
+    stz SPI_BYTES_WRITTEN
-    ; store address in zp
-    lda #<SPI_CODE_START
-    sta code_page
-    lda #>SPI_CODE_START
-    sta code_page + 1
     ; todo USE MASKS
     ; set Shift register to shift in under external clock on CB1
     lda #IO::ACR::SR_SIN_PHIE
@@ -190,49 +64,21 @@ TEST_OUT: .asciiz "TESTOUT"
     ; enable SR interrupts
     lda #(IO::IRQ::IRQ | IO::IRQ::SR)
     sta SPI_IO + IO::IER
-
+    DEBUG_LED_ON 1
-    ; load SR to reset
-    lda SPI_IO + IO::SR
     rts
 .endproc
 
-;********************************************************************************
+.proc spi_p_read
-; @function Stop listening for SPI transfers
+    DEBUG_LED_ON 0
-; @details
+    ; print received byte
-;  Disables shift register interrupts
-;********************************************************************************
-.proc end
-    ; disable SR interrupts
-    lda #IO::IRQ::SR
-    sta SPI_IO + IO::IER
-    rts
-.endproc
-    
-
-
-;********************************************************************************
-; @function Read a byte from SPI
-; @details
-;  Reads a byte from the shift register and stores it in the SPI code buffer
-;********************************************************************************
-.proc read
-    ldx bytes_written
     lda SPI_IO + IO::SR
     sta SPI_CODE_START,x
-    inc bytes_written
+    inc SPI_BYTES_WRITTEN
-    beq @new_page
+    jsr lcd_char
-    rts
-@new_page:
-    inc pages_written
-    inc code_page + 1
     rts
 .endproc
 
     
-;********************************************************************************
-; @function Initialize the IO Adapter for SPI
-; @param ARG0-1 Address of the SPI_Pins struct
-;********************************************************************************
 ;********************************************************************************
 ; @function Read bytes
 ; @param X Number of bytes to send
@@ -250,8 +96,8 @@ TEST_OUT: .asciiz "TESTOUT"
 .proc send_data
 .endproc
 
-.endscope
     
 
+_send_byte:
     
 .endif

util/math.s65

@@ -1,106 +0,0 @@
-;********************************************************************************
-; @module math
-; @type utility
-; @details
-;   Math library
-;********************************************************************************
-.ifndef INCLUDE_MATH
-INCLUDE_MATH = 1
-
-.scope math
-
-;********************************************************************************
-; @macro Divide a num (or A) by a factor
-; @param num: Memory or A
-; @param divider: must be power of 2
-;********************************************************************************
-.macro div num,divider
-.if divider = 2
-    lsr num
-.elseif divider = 4
-    lsr num
-    lsr num
-.elseif divider = 8
-    lsr num
-    lsr num
-    lsr num
-.elseif divider = 16
-    .repeat 4
-    lsr num
-    .endrepeat
-.elseif divider = 32
-    .repeat 5
-    lsr num
-    .endrepeat
-.elseif divider = 64
-    .repeat 6
-    lsr num
-    .endrepeat
-.elseif divider = 128
-    .repeat 7
-    lsr num
-    .endrepeat
-.else
-    .error "div macro: divider % 2 != 0"
-.endif
-.endmacro
-
-; .macro Amult1 factor
-;     phx
-;     ldx factor
-;     AmultX
-;     plx
-; .endmacro
-
-; https://www.llx.com/Neil/a2/mult.html
-; .macro mult num1,num2,result
-;     lda #0
-;     ldx #8
-; L1: 
-;     lsr num2
-;     bcc L2
-;     clc
-;     adc num1
-; L2:
-;     ror
-;     ror result
-;     dex
-;     bne L1
-;     sta result+1
-; .endmacro
-
-;         00110101
-;         10010011
-;         -------^
-;        =00110101
-;        00110101
-;        01001001
-;        -------^
-;       =00110101
-;       00110101
-;       00100100
-;       -------^
-;      =00000000
-;      00110101
-;      00010010
-;      -------^
-;     =00000000
-;     00110101
-;     00001001
-;     -------^
-;     00110101
-;    00110101
-;    00000100
-;    -------^
-;   =00000000
-;   00110101
-;   00000010
-;   -------^
-;  =00000000
-;  00110101
-;  00000001
-; 00110101
-
-      
-.endscope
-.endif  ; guard

util/string.s65

@@ -1,163 +0,0 @@
-;********************************************************************************
-; @module string
-; @type utility
-; @details
-;   String utility
-;********************************************************************************
-.ifndef INCLUDE_STRING
-INCLUDE_STRING = 1
-
-.scope str
-
-.code
-.macro _StrfStoreArg arg
-.if (.not .blank(arg))
-    .if .match(arg, x)
-        stx ARG4 + @N_ARGS
-    .elseif .match(arg, y)
-        sty ARG4 + @N_ARGS
-    .else
-        lda arg
-        sta ARG4 + @N_ARGS
-    .endif
-    @N_ARGS .set (@N_ARGS + 1)
-.endif
-.endmacro
-
-;********************************************************************************
-; @function Macro for passing arguments to strf
-; @param fmt:   Format string address
-; @param out:   Output string address
-; @param x0-x9: Additional parameters
-; @warning Addresses as additional paramteres must be passed like this `#<addr,#>addr`
-; @modifies: A, X, Y
-; @see strf
-;********************************************************************************
-.macro Strf fmt,out,x0,x1,x2,x3,x4,x5,x6,x7,x8,x9
-    @N_ARGS .set 0  ; @ so that it doesnt break cheap labels
-    lda #<fmt
-    sta ARG0
-    lda #>fmt
-    sta ARG1
-    lda #<out
-    sta ARG2
-    lda #>out
-    sta ARG3
-    _StrfStoreArg x0
-    _StrfStoreArg x1
-    _StrfStoreArg x2
-    _StrfStoreArg x3
-    _StrfStoreArg x4
-    _StrfStoreArg x5
-    _StrfStoreArg x6
-    _StrfStoreArg x7
-    jsr strf
-    .out .sprintf("info: Strf: called with %d arguments", @N_ARGS)
-.endmacro
-
-; TODO allocate zp memory
-fmt_idx = $30
-out_idx = $31
-;********************************************************************************
-; @function Format a string
-; @details
-;   If there is no value to be read, the Pz will be set
-;   Formats:
-;   - x: unsigned hex integer (1 byte) -> 2 chars
-;   - X: unsigned hex integer (2 byte) -> 4 chars TODO
-;   - u: unsigned decimal integer (1 byte) TODO
-;   - U: unsigned decimal integer (2 bytes) TODO
-; @param ARG0-1: Format string address
-; @param ARG2-3: Output string address
-; @param ARG4+:  Additional parameters
-; @returns 
-; @modifies: A, X, Y
-;********************************************************************************
-.proc strf
-    stz out_idx
-    stz fmt_idx
-    ldy #0  ; position in string
-    ldx #0  ; index of format args
-@loop:
-    ldy fmt_idx
-    lda (ARG0),y
-    beq @null
-    cmp #'%'
-    beq @percent
-@normal_char:  ; store A in output string
-        ldy out_idx
-        sta (ARG2),y
-        inc fmt_idx
-        inc out_idx
-        beq @out_overflow
-        bra @loop
-@percent:  ; check for format in next position
-        iny
-        sty fmt_idx
-        lda (ARG0),y
-        beq @null
-        ; formats
-        cmp #'x'
-        beq @format_hex1
-        bra @normal_char
-@format_hex1:   ; 1 byte hex -> 2 chars
-            lda ARG4,x
-            phx
-            jsr int8_to_hex_str
-            ldy out_idx
-            sta (ARG2),y  ; most sig digit
-            iny
-            beq @out_overflow
-            txa
-            sta (ARG2),y  ; least sig digit
-            iny
-            beq @out_overflow
-            sty out_idx
-            plx
-            inx  ; 1 byte of args handeled
-            ; bra @format_return
-@format_return:  ; increment fmt_idx to swallow the formating char
-        inc fmt_idx
-        bra @loop
-@out_overflow:  ; store 0 in last position
-    ldy #$ff
-    sty out_idx
-@store_null:
-    lda #0
-@null:  ; store and return
-    ldy out_idx
-    sta (ARG2),y
-@rts:
-    rts
-.endproc
-
-
-;********************************************************************************
-; @function Convert a 1 byte number into two hex characters
-; @param A: Number to convert
-; @returns A: Most significant digit
-; @returns X: Least significant digit
-; @modifies A,X,Y
-;********************************************************************************
-.proc int8_to_hex_str
-    pha
-    and #%00001111
-    tay
-    ldx HEX_CHARS_UPPER,y
-    pla
-    div A,16
-    and #%00001111
-    tay
-    lda HEX_CHARS_UPPER,y
-    rts
-.endproc
-
-
-.rodata
-HEX_CHARS_UPPER:    .byte "0123456789ABCDEF"
-HEX_CHARS_LOWER:    .byte "0123456789abcdef"
-
-.export strf
-
-.endscope
-.endif  ; guard