;********************************************************************************
; @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