bsv.c

   1 #include <stdio.h>
   2 #include "fakeasm.h"
   3 typedef unsigned char u8;
   4
   5 u8 notes[16]; //MEM
   6 u8 i0, i1, i2; //MEM
   7 u8 n; //MEM
   8 u8 sample; //MEM
   9 u8 tmp_1; //MEM
  10 u8 acc; //ACC
  11
  12 u8 mod3hi, mod3lo; //MEM
  13 //todo: can mod3hi be aliased to tmp_1?
  14 void mod3(void) {
  15         MOV     (acc,mod3hi)
  16         ADD     (mod3lo,acc) // mod3lo = hi+lo
  17         CLEAR   (acc)
  18         ADDC0   (acc) // mod3hi, 1bit
  19         SWAP    (acc)
  20         MOV     (mod3hi, acc)
  21
  22         MOV     (acc, mod3lo)
  23         SWAP    (acc)
  24         AND     (acc, 0xf) // (mod3lo>>4)
  25         XCH     (mod3lo) // acc=mod3lo, mod3lo=mod3lo>>4
  26         AND     (acc, 0xF) // acc=mod3lo&0xf, mod3lo=mod3lo>>4
  27         ADD     (acc, mod3lo) // (mod3lo & 0xF)
  28         ADD     (acc, mod3hi)
  29         MOV     (mod3lo, acc)
  30
  31         AND     (acc, 0x3) // acc = (mod3lo & 0x3)
  32         SR      (mod3lo)
  33         SR      (mod3lo) // (mod3lo >>  2)
  34         ADD     (acc, mod3lo)
  35         MOV     (mod3lo, acc)
  36
  37         AND     (acc, 0x3) // acc = (mod3lo & 0x3)
  38         SR      (mod3lo)
  39         SR      (mod3lo) // (mod3lo >>  2)
  40         ADD     (acc, mod3lo)
  41
  42         SUB     (acc,3)
  43         if (flag_c){ // T0SN FLAG.C (0x00.1) -- skip if carry clear
  44                 ADD (acc,3)
  45         }
  46 }
  47
  48 void g(void){
  49         u8 notes_ix = acc & 0x7;
  50         if(3&i2)
  51                 notes_ix += 8;
  52         u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
  53         acc = result;
  54 }
  55 void main(void){
  56         CLEAR   (i0)
  57         CLEAR   (i1)
  58         CLEAR   (i2)
  59
  60         //rom is not mmapped; must load into ram first
  61         MOV     (acc, 0x84)
  62         MOV     (notes[0x0], acc)
  63         MOV     (notes[0x5], acc)
  64         MOV     (acc, 0x9d)
  65         MOV     (notes[0x1], acc)
  66         MOV     (notes[0x4], acc)
  67         MOV     (acc, 0xb0)
  68         MOV     (notes[0x2], acc)
  69         MOV     (notes[0xA], acc)
  70         MOV     (acc, 0x69)
  71         MOV     (notes[0x3], acc)
  72         MOV     (notes[0x6], acc)
  73         MOV     (notes[0xB], acc)
  74         MOV     (notes[0xE], acc)
  75         MOV     (acc, 0x58)
  76         MOV     (notes[0x7], acc)
  77         MOV     (notes[0xF], acc)
  78         MOV     (acc, 0x75)
  79         MOV     (notes[0x8], acc)
  80         MOV     (notes[0xD], acc)
  81         MOV     (acc, 0x8c)
  82         MOV     (notes[0x9], acc)
  83         MOV     (notes[0xC], acc)
  84
  85         for(;;) {
  86                 MOV     (acc, i2)// "mov mem,mem"
  87                 MOV     (n, acc)// does not exist
  88                 SL      (n)
  89                 SL      (n)
  90                 MOV     (acc, i1)
  91                 SWAP    (acc)
  92                 AND     (acc, 0xf)
  93                 SR      (acc)
  94                 SR      (acc)
  95                 OR      (n, acc)
  96
  97                 MOV     (acc, n)
  98                 CALL    (g)
  99                 SWAP    (acc)
 100                 AND     (acc, 0x1)
 101                 MOV     (sample, acc)
 102
 103                 MOV     (acc, i2)
 104                 SL      (acc)
 105                 SL      (acc)
 106                 SL      (acc)
 107                 MOV     (tmp_1, acc) // fresh tmp_1:
 108                 MOV     (acc, i1)
 109                 SWAP    (acc)
 110                 AND     (acc, 0xf)
 111                 SR      (acc)
 112                 OR      (acc, tmp_1) // tmp_1 done.
 113                 XOR     (acc, n)
 114                 CALL    (g)
 115                 SR      (acc)
 116                 AND     (acc, i2)
 117                 SR      (acc)
 118                 AND     (acc, 3)
 119                 ADD     (sample, acc)
 120
 121                 MOV     (acc, i2)
 122                 MOV     (mod3hi, acc)
 123                 SR      (mod3hi)
 124                 SR      (mod3hi)
 125                 SR      (mod3hi)
 126                 SWAP    (acc)
 127                 AND     (acc, 0xf0)
 128                 SL      (acc)
 129                 MOV     (mod3lo, acc)
 130                 MOV     (acc, i1)
 131                 SR      (acc)
 132                 SR      (acc)
 133                 SR      (acc)
 134                 OR      (mod3lo, acc)
 135                 CALL    (mod3)
 136                 ADD     (acc, n)
 137                 CALL    (g)
 138                 SR      (acc)
 139                 SR      (acc)
 140                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 141                 MOV     (acc, i2)
 142                 // shift-divide by six
 143                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
 144                 SR      (acc)
 145                 ADD     (acc, i2)
 146                 SR      (acc)
 147                 SR      (acc)
 148                 ADD     (acc, i2)
 149                 SR      (acc)
 150                 SR      (acc)
 151                 ADD     (acc, i2)
 152                 SR      (acc)
 153                 SR      (acc)
 154                 SR      (acc)
 155                 // end divide by six
 156                 AND     (acc, tmp_1) // acc restored from tmp_1
 157                 AND     (acc, 3)
 158                 ADD     (sample, acc)
 159
 160                 MOV     (acc, i2)
 161                 MOV     (mod3hi, acc)
 162                 SR      (mod3hi)
 163                 SR      (mod3hi)
 164                 SWAP    (acc)
 165                 AND     (acc, 0xf0)
 166                 SL      (acc)
 167                 SL      (acc)
 168                 MOV     (mod3lo, acc)
 169                 MOV     (acc, i1)
 170                 SR      (acc)
 171                 SR      (acc)
 172                 OR      (mod3lo, acc)
 173                 CALL    (mod3)
 174                 SUB     (acc, n)
 175                 SUB     (acc, 8)
 176                 NEG     (acc)
 177                 CALL    (g)
 178                 SR      (acc)
 179                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 180                 MOV     (acc, i2)
 181                 // shift-divide by ten
 182                 // note: i2 is max 0x78; so acc will <= 12.
 183                 INC     (i2)
 184                 SR      (acc)
 185                 ADD     (acc, i2)
 186                 SR      (acc)
 187                 SR      (acc)
 188                 SR      (acc)
 189                 ADD     (acc, i2)
 190                 SR      (acc)
 191                 ADD     (acc, i2)
 192                 SWAP    (acc)
 193                 DEC     (i2)
 194                 // end divide by ten
 195                 AND     (acc, tmp_1) // acc restored from tmp_1
 196                 AND     (acc, 3)
 197                 ADD     (sample, acc)
 198
 199                 MOV     (acc, sample)
 200                 SWAP    (acc)
 201                 putchar(acc);
 202
 203                 INC     (i0)
 204                 i1 += !i0; // ADDC i1
 205                 i2 += !i1 && !i0; // ADDC i2
 206
 207                 if(i2 == 0x78) break;
 208         }
 209 }