save 12 more bytes, 7368 free, document the hell out of console.s

2 files changed, 49 insertions, 9 deletions

diff --git a/console.s b/console.s
index 7837ce1..1930303 100644
--- a/console.s
+++ b/console.s
@@ -138,7 +138,32 @@ _rvs_off:
  ; ...or 5 bytes each. we have 5 of them, so 25 bytes. using fall-thru
  ; and the BIT trick, they condense down to 17 bytes.
  ; if you're not familiar with the "BIT trick" to skip a 2-byte instruction,
- ; the stuff below looks like gibberish, sorry.
+ ; the stuff below looks like gibberish... here's a mini-tutorial:
+
+ ;store1:
+ ; lda #1
+ ; .byte $2c ; this is the opcode for BIT absolute
+ ;store2:
+ ; lda #2
+ ; sta $0600
+ ; rts
+
+ ; if entered via "jsr store1", the above code fragment executes these
+ ; instructions:
+ ; lda #1
+ ; bit $02A9 ; $A9 is the LDA immediate opcode, 02 is the #2
+ ; sta $0600
+ ; rts
+
+ ; if entered via "jsr store2", it's
+ ; lda #2
+ ; sta $0600
+ ; rts
+
+ ; the "bit $02a9' doesn't affect any registers other than the flags,
+ ; and the "sta $0600 : rts" part doesn't depend on any of the flags,
+ ; so the BIT is effectively a no-op that "masks" the 2-byte LDA #2
+ ; instruction "hidden" as its operand.
 
  ; ", Taipan? "
  ; using fall-thru here saves 3 bytes (normally the last instruction
diff --git a/taipan.c b/taipan.c
index e221fc5..ef10068 100644
--- a/taipan.c
+++ b/taipan.c
@@ -316,7 +316,7 @@ unsigned long __fastcall__ strtonum(const char* nptr);
 
 unsigned char firmpos;
 
-/* use page 6 for these buffers, for .xex build. Otherwise they'e BSS. */
+/* use page 6 for these buffers, for .xex build. Otherwise they're BSS. */
 #ifdef CART_TARGET
 char firm[23];
 char num_buf[20];
@@ -779,15 +779,17 @@ void new_gun(void) {
    return;
 }
 
+/* cprintfancy_centered() does this for 0 to 999999:
+	|   999999   |
+	|   99999    |
+	|    9999    |
+	|    999     |
+	|     99     |
+	|     9      | */
+
+#if 0
 void cprintfancy_centered(unsigned long num) {
 	if(num < 1000000L) {
-		/* 0 to 999999:
-			|   999999   |
-			|   99999    |
-			|    9999    |
-			|    999     |
-			|     99     |
-			|     9      | */
 		cspaces(3);
 		if(num < 100L) cspace();
 		if(num < 10000L) cspace();
@@ -799,6 +801,19 @@ void cprintfancy_centered(unsigned long num) {
 	}
 	rvs_off();
 }
+#else
+// saves 12 bytes:
+void cprintfancy_centered(unsigned long num) {
+	if(num < 1000000L) {
+		cspaces(3);
+		if(num < 100L) cspace();
+		if(num < 10000L) cspace();
+	}
+	rvs_on();
+	cprintfancy(num);
+	rvs_off();
+}
+#endif
 
 /* if BIGNUM, cprintfancy() just converts to bignum and uses
 	cprintfancy_big() to do the work. A bit slower, but fast