diff options
Diffstat (limited to 'src/txbuf.s')
| -rw-r--r-- | src/txbuf.s | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/src/txbuf.s b/src/txbuf.s new file mode 100644 index 0000000..bc1d1c2 --- /dev/null +++ b/src/txbuf.s @@ -0,0 +1,50 @@ +;; 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 |