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;; void txbuf_append_chr(char c) {
;; tx_buf[txbuflen++] = c;
;; }
; compiles to 45 bytes. routine below is 29 bytes (~33% smaller)
tx_buf = $a200 ; MUST agree with src/rxtxbuf.h!
.import _txbuflen
.export _txbuf_append_chr, _txbuf_append_str
.importzp sreg ; avoid ptr1 & friends, callers may use
_txbuf_append_chr:
tax
lda #<tx_buf
clc
adc _txbuflen
sta sreg
lda #>tx_buf
adc _txbuflen+1
sta sreg+1
ldy #0
txa
sta (sreg),y
inc _txbuflen
bne ret
inc _txbuflen+1
ret:
rts ; always returns with Y == 0
;; void txbuf_append_str(const char *str) {
;; while(*str) {
;; txbuf_append_chr(*str++);
;; }
;; }
; compiles to 52 bytes.
; this routine is 22 bytes, ~57% smaller.
_txbuf_append_str:
sta sreg+2
stx sreg+3
ldy #0
@loop:
lda (sreg+2),y
beq ret
jsr _txbuf_append_chr
inc sreg+2
bne @loop
inc sreg+3
bne @loop
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