bsv.c

   1 #include <stdio.h>
   2 #include "fakeasm.h"
   3 typedef unsigned char u8;
   4
   5 u8 i0, i1, i2; //MEM
   6 u8 n; //MEM
   7 u8 sample; //MEM
   8 u8 tmp_1; //MEM
   9 u8 acc; //ACC
  10
  11 u8 notes[] = {
  12         0x84, 0x9d, 0xb0, 0x69, 0x9d, 0x84, 0x69, 0x58,
  13         0x75, 0x8c, 0xb0, 0x69, 0x8c, 0x75, 0x69, 0x58
  14 };
  15
  16 u8 mod3hi, mod3lo; //MEM
  17 void mod3(void) {
  18                 u8 x = (mod3hi+mod3lo)>>8;
  19         MOV(acc,mod3hi)
  20         ADD(mod3lo,acc) // mod3lo = hi+lo
  21                 flag_c = x;
  22         CLEAR(acc)
  23         ADDC0(acc) // mod3hi, 1bit
  24         SWAP(acc)
  25         MOV(mod3hi, acc)
  26
  27         mod3lo = mod3hi + (mod3lo>>4) + (mod3lo & 0xF);
  28         mod3lo = (mod3lo >>  2) + (mod3lo & 0x3);
  29         mod3lo = (mod3lo >>  2) + (mod3lo & 0x3);
  30         if (mod3lo > 2) mod3lo = mod3lo - 3;
  31         acc = mod3lo;
  32 }
  33
  34 void g(void){
  35         u8 notes_ix = acc & 0x7;
  36         if(3&i2)
  37                 notes_ix += 8;
  38         u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
  39         acc = result;
  40 }
  41 void main(void){
  42         CLEAR   (i0)
  43         CLEAR   (i1)
  44         CLEAR   (i2)
  45         for(;;) {
  46                 MOV     (acc, i2)// "mov mem,mem"
  47                 MOV     (n, acc)// does not exist
  48                 SL      (n)
  49                 SL      (n)
  50                 MOV     (acc, i1)
  51                 SWAP    (acc)
  52                 AND     (acc, 0xf)
  53                 SR      (acc)
  54                 SR      (acc)
  55                 OR      (n, acc)
  56
  57                 MOV     (acc, n)
  58                 CALL    (g)
  59                 SWAP    (acc)
  60                 AND     (acc, 0x1)
  61                 MOV     (sample, acc)
  62
  63                 MOV     (acc, i2)
  64                 SL      (acc)
  65                 SL      (acc)
  66                 SL      (acc)
  67                 MOV     (tmp_1, acc) // fresh tmp_1:
  68                 MOV     (acc, i1)
  69                 SWAP    (acc)
  70                 AND     (acc, 0xf)
  71                 SR      (acc)
  72                 OR      (acc, tmp_1) // tmp_1 done.
  73                 XOR     (acc, n)
  74                 CALL    (g)
  75                 SR      (acc)
  76                 AND     (acc, i2)
  77                 SR      (acc)
  78                 AND     (acc, 3)
  79                 ADD     (sample, acc)
  80
  81                 mod3hi = i2>>3;
  82                 mod3lo = i2<<5|i1>>3;
  83                 CALL    (mod3)
  84                 ADD     (acc, n)
  85                 CALL    (g)
  86                 SR      (acc)
  87                 SR      (acc)
  88                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
  89                 MOV     (acc, i2)
  90                 // shift-divide by six
  91                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
  92                 SR      (acc)
  93                 ADD     (acc, i2)
  94                 SR      (acc)
  95                 SR      (acc)
  96                 ADD     (acc, i2)
  97                 SR      (acc)
  98                 SR      (acc)
  99                 ADD     (acc, i2)
 100                 SR      (acc)
 101                 SR      (acc)
 102                 SR      (acc)
 103                 // end divide by six
 104                 AND     (acc, tmp_1) // acc restored from tmp_1
 105                 AND     (acc, 3)
 106                 ADD     (sample, acc)
 107
 108                 mod3hi = i2>>2;
 109                 mod3lo = i2<<6|i1>>2;
 110                 CALL    (mod3)
 111                 SUB     (acc, n)
 112                 SUB     (acc, 8)
 113                 NEG     (acc)
 114                 CALL    (g)
 115                 SR      (acc)
 116                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 117                 MOV     (acc, i2)
 118                 // shift-divide by ten
 119                 // note: i2 is max 0x78; so acc will <= 12.
 120                 INC     (i2)
 121                 SR      (acc)
 122                 ADD     (acc, i2)
 123                 SR      (acc)
 124                 SR      (acc)
 125                 SR      (acc)
 126                 ADD     (acc, i2)
 127                 SR      (acc)
 128                 ADD     (acc, i2)
 129                 SWAP    (acc)
 130                 DEC     (i2)
 131                 // end divide by ten
 132                 AND     (acc, tmp_1) // acc restored from tmp_1
 133                 AND     (acc, 3)
 134                 ADD     (sample, acc)
 135
 136                 MOV     (acc, sample)
 137                 SWAP    (acc)
 138                 putchar(acc);
 139
 140                 INC     (i0)
 141                 i1 += !i0; // ADDC i1
 142                 i2 += !i1 && !i0; // ADDC i2
 143         }
 144 }