new version

[Chiptunes.git] / foo.c

diff --git a/foo.c b/foo.c
index 29ddee4be58b0f51c2e5b566dd052563a20ffa10..9ef065b215809c227537181672cd28580a430bb2 100644 (file)
--- 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) {