X-Git-Url: https://git.gir.st/Chiptunes.git/blobdiff_plain/e8142e8fc65c5a43f5ef715391d2d89fb585e1e6..be76bfa858937c821630cdcc1c54d12d0059b476:/foo.c

diff --git a/foo.c b/foo.c
index 29ddee4..9ef065b 100644
--- a/foo.c
+++ b/foo.c
@@ -86,7 +86,8 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 	  LD   Zhi, X
 	  IJMP Z */
 
-	mul_58: // 0101 1000 (24cy)
+	//don't care about top three bits (so don't compute them => _)
+	mul_58: // ___1 1000 (24cy)
 		LSR (a2)
 		ROR (a1)
 		LSR (a2)
@@ -102,14 +103,11 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 		ADC (a2, i1, carry)
 		LSR (a2)
 		ROR (a1)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
 		RJMP	(endmul)
-	mul_69: // 0110 1001 (26cy)
+	mul_69: // ___0 1001 (26cy)
 		ADD (a1, i0)
 		ADC (a2, i1, carry)
 		LSR (a2)
@@ -126,15 +124,11 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 		LSR (a2)
 		ROR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
 		RJMP	(endmul)
-	mul_75: // 0111 0101 (28cy)
+	mul_75: // ___1 0101 (28cy)
 		ADD (a1, i0)
 		ADC (a2, i1, carry)
 		LSR (a2)
@@ -153,15 +147,11 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 		LSR (a2)
 		ROR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
 		RJMP	(endmul)
-	mul_84: // 1000 0100 (22cy)
+	mul_84: // ___0 0100 (22cy)
 		LSR (a2)
 		ROR (a1)
 		LSR (a2)
@@ -175,14 +165,11 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 
 		LSR (a2)
 		ROR (a1)
-		LSR (a2)
-		ROR (a1)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
 		RJMP	(endmul)
-	mul_8c: // 1000 1100 (24cy)
+	mul_8c: // ___0 1100 (24cy)
 		LSR (a2)
 		ROR (a1)
 		LSR (a2)
@@ -198,14 +185,11 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 
 		LSR (a2)
 		ROR (a1)
-		LSR (a2)
-		ROR (a1)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
 		RJMP	(endmul)
-	mul_9d: // 1001 1101 (28cy)
+	mul_9d: // ___1 1101 (28cy)
 		ADD (a1, i0)
 		ADC (a2, i1, carry)
 		LSR (a2)
@@ -225,14 +209,11 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 		ADC (a2, i1, carry)
 		LSR (a2)
 		ROR (a1)
-		LSR (a2)
-		ROR (a1)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
 		RJMP	(endmul)
-	mul_b0: // 1011 0000 (22cy)
+	mul_b0: // ___1 0000 (22cy)
 		LSR (a2)
 		ROR (a1)
 		LSR (a2)
@@ -247,22 +228,17 @@ static void* mul_jmptable[] = { // replaces data[] section at the top
 		LSR (a2)
 		ROR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
-		LSR (a2)
-		ROR (a1)
-		LSR (a2)
-		ROR (a1)
+		LSR (a1)
+		LSR (a1)
 		ADD (a1, i0)
-		ADC (a2, i1, carry)
 	endmul:
-		LSR (a2) //final shift is a common operation for all
-		ROR (a1)
+		LSR (a1) //final shift is a common operation for all
 	// end MUL
 	MOV	(t, a1)
 	#undef a0
 	#undef a1
 	#undef a2
-	RET //TODO: replace CALL/RET with IJMP?
+	RET //TODO: replace CALL/RET with IJMP? (requires undoing goto-mul-hack)
 };
 
 int main(void) {