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 //todo: can mod3hi be aliased to tmp_1?
  18 void mod3(void) {
  19         MOV     (acc,mod3hi)
  20         ADD     (mod3lo,acc) // mod3lo = hi+lo
  21         CLEAR   (acc)
  22         ADDC0   (acc) // mod3hi, 1bit
  23         SWAP    (acc)
  24         MOV     (mod3hi, acc)
  25
  26         MOV     (acc, mod3lo)
  27         SWAP    (acc)
  28         AND     (acc, 0xf) // (mod3lo>>4)
  29         XCH     (mod3lo) // acc=mod3lo, mod3lo=mod3lo>>4
  30         AND     (acc, 0xF) // acc=mod3lo&0xf, mod3lo=mod3lo>>4
  31         ADD     (acc, mod3lo) // (mod3lo & 0xF)
  32         ADD     (acc, mod3hi)
  33         MOV     (mod3lo, acc)
  34
  35         AND     (acc, 0x3) // acc = (mod3lo & 0x3)
  36         SR      (mod3lo)
  37         SR      (mod3lo) // (mod3lo >>  2)
  38         ADD     (acc, mod3lo)
  39         MOV     (mod3lo, acc)
  40
  41         AND     (acc, 0x3) // acc = (mod3lo & 0x3)
  42         SR      (mod3lo)
  43         SR      (mod3lo) // (mod3lo >>  2)
  44         ADD     (acc, mod3lo)
  45
  46         if (acc > 2) { // TODO: acc in [0,1,2,3,4]
  47         SUB     (acc,3)
  48         }
  49 }
  50
  51 void g(void){
  52         u8 notes_ix = acc & 0x7;
  53         if(3&i2)
  54                 notes_ix += 8;
  55         u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
  56         acc = result;
  57 }
  58 void main(void){
  59         CLEAR   (i0)
  60         CLEAR   (i1)
  61         CLEAR   (i2)
  62         for(;;) {
  63                 MOV     (acc, i2)// "mov mem,mem"
  64                 MOV     (n, acc)// does not exist
  65                 SL      (n)
  66                 SL      (n)
  67                 MOV     (acc, i1)
  68                 SWAP    (acc)
  69                 AND     (acc, 0xf)
  70                 SR      (acc)
  71                 SR      (acc)
  72                 OR      (n, acc)
  73
  74                 MOV     (acc, n)
  75                 CALL    (g)
  76                 SWAP    (acc)
  77                 AND     (acc, 0x1)
  78                 MOV     (sample, acc)
  79
  80                 MOV     (acc, i2)
  81                 SL      (acc)
  82                 SL      (acc)
  83                 SL      (acc)
  84                 MOV     (tmp_1, acc) // fresh tmp_1:
  85                 MOV     (acc, i1)
  86                 SWAP    (acc)
  87                 AND     (acc, 0xf)
  88                 SR      (acc)
  89                 OR      (acc, tmp_1) // tmp_1 done.
  90                 XOR     (acc, n)
  91                 CALL    (g)
  92                 SR      (acc)
  93                 AND     (acc, i2)
  94                 SR      (acc)
  95                 AND     (acc, 3)
  96                 ADD     (sample, acc)
  97
  98                 MOV     (acc, i2)
  99                 MOV     (mod3hi, acc)
 100                 SR      (mod3hi)
 101                 SR      (mod3hi)
 102                 SR      (mod3hi)
 103                 SWAP    (acc)
 104                 AND     (acc, 0xf0)
 105                 SL      (acc)
 106                 MOV     (mod3lo, acc)
 107                 MOV     (acc, i1)
 108                 SR      (acc)
 109                 SR      (acc)
 110                 SR      (acc)
 111                 OR      (mod3lo, acc)
 112                 CALL    (mod3)
 113                 ADD     (acc, n)
 114                 CALL    (g)
 115                 SR      (acc)
 116                 SR      (acc)
 117                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 118                 MOV     (acc, i2)
 119                 // shift-divide by six
 120                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
 121                 SR      (acc)
 122                 ADD     (acc, i2)
 123                 SR      (acc)
 124                 SR      (acc)
 125                 ADD     (acc, i2)
 126                 SR      (acc)
 127                 SR      (acc)
 128                 ADD     (acc, i2)
 129                 SR      (acc)
 130                 SR      (acc)
 131                 SR      (acc)
 132                 // end divide by six
 133                 AND     (acc, tmp_1) // acc restored from tmp_1
 134                 AND     (acc, 3)
 135                 ADD     (sample, acc)
 136
 137                 mod3hi = i2>>2;
 138                 MOV     (acc, i2)
 139                 SWAP    (acc)
 140                 AND     (acc, 0xf0)
 141                 SL      (acc)
 142                 SL      (acc)
 143                 MOV     (mod3lo, acc)
 144                 MOV     (acc, i1)
 145                 SR      (acc)
 146                 SR      (acc)
 147                 OR      (mod3lo, acc)
 148
 149                 CALL    (mod3)
 150                 SUB     (acc, n)
 151                 SUB     (acc, 8)
 152                 NEG     (acc)
 153                 CALL    (g)
 154                 SR      (acc)
 155                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 156                 MOV     (acc, i2)
 157                 // shift-divide by ten
 158                 // note: i2 is max 0x78; so acc will <= 12.
 159                 INC     (i2)
 160                 SR      (acc)
 161                 ADD     (acc, i2)
 162                 SR      (acc)
 163                 SR      (acc)
 164                 SR      (acc)
 165                 ADD     (acc, i2)
 166                 SR      (acc)
 167                 ADD     (acc, i2)
 168                 SWAP    (acc)
 169                 DEC     (i2)
 170                 // end divide by ten
 171                 AND     (acc, tmp_1) // acc restored from tmp_1
 172                 AND     (acc, 3)
 173                 ADD     (sample, acc)
 174
 175                 MOV     (acc, sample)
 176                 SWAP    (acc)
 177                 putchar(acc);
 178
 179                 INC     (i0)
 180                 i1 += !i0; // ADDC i1
 181                 i2 += !i1 && !i0; // ADDC i2
 182
 183                 if(i2 == 0x78) break;
 184         }
 185 }