ASM read byte (gcc)

    .feature at_in_identifiers
    .feature dollar_in_identifiers
    .autoimport +
    .pc02
    .importzp _sp0, _sp1, _fp0, _fp1
    .importzp _r0, _r1, _r2, _r3, _r4, _r5, _r6, _r7
    .importzp _s0, _s1, _s2, _s3, _s4, _s5, _s6, _s7
    .importzp _e0, _e1, _e2, _e3, _e4, _e5, _e6, _e7
    .importzp _e8, _e9, _e10, _e11, _e12, _e13, _e14, _e15
    .importzp _e16, _e17, _e18, _e19, _e20, _e21, _e22, _e23
    .importzp _e24, _e25, _e26, _e27, _e28, _e29, _e30, _e31
    .importzp _tmp0, _tmp1
    .importzp _sa, _sx, _sy
    .code
    .segment "CODE"
    .segment "RODATA"
LC@0:
    .byte "ARQUIVO3.BIN", $0
LC@1:
    .byte "error %D", $0
    .segment "CODE"
    .export main
main:
; frame size 0, pretend size 0, outgoing size 0
    stz $0002
    lda #$b0
    sta $0003
    lda #$01
    sta _r2
    lda #$08
    sta _r1
    lda #$01
    sta _r0
    jsr cbm_k_setlfs
    lda #<(LC@0)
    sta _r0
    lda #>(LC@0)
    sta _r1
    jsr cbm_k_setnam
    jsr cbm_k_open
    lda #$01
    sta _r0
    jsr cbm_k_chkin
    jsr cbm_k_readst
    lda _r0
    bne L@10
    jsr cbm_k_basin
;# 119 "gcc_cx16.h" 1
    lda _r0
;# 120 "gcc_cx16.h" 1
    jsr $FFD2
    rts
L@10:
    sta _r2
    stz _r3
    lda #<(LC@1)
    sta _r0
    lda #>(LC@1)
    sta _r1
    jsr printf
    rts