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cc65/libsrc/kim1/read.s
Jeff Tranter 806ffe5675 Fixes and improvements to KIM-1 i/o routines.
Tested on real KIM-1 hardware.

read.s:
- Remove commented out line.
- Remove unused check for bell character.
- Remove echo of newline (hardware always echoes entered characters).
- This fixes gets() and fgets() so they return when CR is entered.

write.s:
- Fix check for adding return after linefeed (failed to work because OUTCHR changes A)
- Remove unused check for bell character.

kim1.inc:
- Add symbol for monitor entry

crt0.s:
- Jump to KIM-1 monitor by address rather than using BRK (which relies on vector being set in RAM)
2023-03-27 17:56:25 -04:00

47 lines
1.2 KiB
ArmAsm

;
; int __fastcall__ read (int fd, void* buf, unsigned count);
;
.include "kim1.inc"
.import popax, popptr1
.importzp ptr1, ptr2, ptr3
.export _read
.proc _read
sta ptr3
stx ptr3+1 ; Count in ptr3
inx
stx ptr2+1 ; Increment and store in ptr2
tax
inx
stx ptr2
jsr popptr1 ; Buffer address in ptr1
jsr popax
begin: dec ptr2
bne getch
dec ptr2+1
beq done ; If buffer full, return
getch: jsr INTCHR ; Get character using Monitor ROM call
and #$7F ; Clear top bit
cmp #$0D ; Check for '\r'
bne putch ; ...if CR character
lda #$0A ; Replace with '\n'
putch: ldy #$00 ; Put char into return buffer
sta (ptr1),y
inc ptr1 ; Increment pointer
bne begin
inc ptr1+1
bne begin
done: lda ptr3
ldx ptr3+1
rts ; Return count
.endproc