Rewrite most of the txbuf_* functions in asm. 7803 bytes free.

1 files changed, 32 insertions, 1 deletions

diff --git a/src/txbuf.s b/src/txbuf.s
index dba52c3..6f7b55d 100644
--- a/src/txbuf.s
+++ b/src/txbuf.s
@@ -6,11 +6,25 @@
 
  tx_buf = $a200 ; MUST agree with src/rxtxbuf.h!
 
- .import _txbuflen
+ .import _txbuflen, _txbuf_send
  .export _txbuf_append_chr, _txbuf_append_str
  .export _txbuf_append_spc, _txbuf_append_01
+ .export _txbuf_init, _txbuf_set_str, _txbuf_send_str
  .importzp sreg ; avoid ptr1 & friends, callers may use
 
+;; void txbuf_init(void) {
+;; 	txbuflen = tx_buf[0] = 0;
+;; }
+; this asm implementation is the same size as the compiled code,
+; but it only uses the Y register, which lets its callers avoid
+; having to save the A register before calling it.
+_txbuf_init:
+ ldy #0
+ sty tx_buf
+ sty _txbuflen
+ sty _txbuflen+1
+ rts
+
 _txbuf_append_01:
  lda #$01
  .byte $2c ; BIT abs, skip next instruction
@@ -34,6 +48,14 @@ _txbuf_append_chr:
 ret:
  rts ; always returns with Y == 0
 
+;; void txbuf_set_str(const char *str) {
+;; 	txbuf_init();
+;; 	txbuf_append_str(str);
+;; }
+_txbuf_set_str:
+ jsr _txbuf_init ; remember, this doesn't touch A or X!
+ ; fall through to _txbuf_append_str
+
 ;; void txbuf_append_str(const char *str) {
 ;; 	while(*str) {
 ;; 		txbuf_append_chr(*str++);
@@ -54,3 +76,12 @@ _txbuf_append_str:
  bne @loop
  inc sreg+3
  bne @loop
+ rts ; safety net, the above is really a 'branch always'
+
+;; void txbuf_send_str(const char *str) {
+;; 	txbuf_set_str(str);
+;; 	txbuf_send();
+;; }
+_txbuf_send_str:
+ jsr _txbuf_set_str
+ jmp _txbuf_send