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                 mod3lo = i2<<6|i1>>2;
 139                 CALL    (mod3)
 140                 SUB     (acc, n)
 141                 SUB     (acc, 8)
 142                 NEG     (acc)
 143                 CALL    (g)
 144                 SR      (acc)
 145                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 146                 MOV     (acc, i2)
 147                 // shift-divide by ten
 148                 // note: i2 is max 0x78; so acc will <= 12.
 149                 INC     (i2)
 150                 SR      (acc)
 151                 ADD     (acc, i2)
 152                 SR      (acc)
 153                 SR      (acc)
 154                 SR      (acc)
 155                 ADD     (acc, i2)
 156                 SR      (acc)
 157                 ADD     (acc, i2)
 158                 SWAP    (acc)
 159                 DEC     (i2)
 160                 // end divide by ten
 161                 AND     (acc, tmp_1) // acc restored from tmp_1
 162                 AND     (acc, 3)
 163                 ADD     (sample, acc)
 164
 165                 MOV     (acc, sample)
 166                 SWAP    (acc)
 167                 putchar(acc);
 168
 169                 INC     (i0)
 170                 i1 += !i0; // ADDC i1
 171                 i2 += !i1 && !i0; // ADDC i2
 172
 173                 if(i2 == 0x78) break;
 174         }
 175 }