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         // notes_ix_hi = always 0
  50         u8 notes_ix;//lo
  51         AND     (acc, 0x7)
  52         MOV     (notes_ix, acc)
  53         // test i2 & 3:
  54         MOV     (acc, i2)
  55         AND     (acc, 3)
  56         if(3&i2) {// T0SN FLAG.Z (0x00.0) -- skip if !(3&i0)
  57                 notes_ix |= 8; // SET1 MEM.n
  58         }
  59         acc = notes[notes_ix]; // IDXM acc, notes_ix
  60         u8 result = ((i1<<8|i0)*acc)>>8;  // keep hi byte
  61         acc = result;
  62 }
  63 void main(void){
  64         CLEAR   (i0)
  65         CLEAR   (i1)
  66         CLEAR   (i2)
  67
  68         //rom is not mmapped; must load into ram first
  69         MOV     (acc, 0x84)
  70         MOV     (notes[0x0], acc)
  71         MOV     (notes[0x5], acc)
  72         MOV     (acc, 0x9d)
  73         MOV     (notes[0x1], acc)
  74         MOV     (notes[0x4], acc)
  75         MOV     (acc, 0xb0)
  76         MOV     (notes[0x2], acc)
  77         MOV     (notes[0xA], acc)
  78         MOV     (acc, 0x69)
  79         MOV     (notes[0x3], acc)
  80         MOV     (notes[0x6], acc)
  81         MOV     (notes[0xB], acc)
  82         MOV     (notes[0xE], acc)
  83         MOV     (acc, 0x58)
  84         MOV     (notes[0x7], acc)
  85         MOV     (notes[0xF], acc)
  86         MOV     (acc, 0x75)
  87         MOV     (notes[0x8], acc)
  88         MOV     (notes[0xD], acc)
  89         MOV     (acc, 0x8c)
  90         MOV     (notes[0x9], acc)
  91         MOV     (notes[0xC], acc)
  92
  93         for(;;) {
  94                 MOV     (acc, i2)// "mov mem,mem"
  95                 MOV     (n, acc)// does not exist
  96                 SL      (n)
  97                 SL      (n)
  98                 MOV     (acc, i1)
  99                 SWAP    (acc)
 100                 AND     (acc, 0xf)
 101                 SR      (acc)
 102                 SR      (acc)
 103                 OR      (n, acc)
 104
 105                 MOV     (acc, n)
 106                 CALL    (g)
 107                 SWAP    (acc)
 108                 AND     (acc, 0x1)
 109                 MOV     (sample, acc)
 110
 111                 MOV     (acc, i2)
 112                 SL      (acc)
 113                 SL      (acc)
 114                 SL      (acc)
 115                 MOV     (tmp_1, acc) // fresh tmp_1:
 116                 MOV     (acc, i1)
 117                 SWAP    (acc)
 118                 AND     (acc, 0xf)
 119                 SR      (acc)
 120                 OR      (acc, tmp_1) // tmp_1 done.
 121                 XOR     (acc, n)
 122                 CALL    (g)
 123                 SR      (acc)
 124                 AND     (acc, i2)
 125                 SR      (acc)
 126                 AND     (acc, 3)
 127                 ADD     (sample, acc)
 128
 129                 MOV     (acc, i2)
 130                 MOV     (mod3hi, acc)
 131                 SR      (mod3hi)
 132                 SR      (mod3hi)
 133                 SR      (mod3hi)
 134                 SWAP    (acc)
 135                 AND     (acc, 0xf0)
 136                 SL      (acc)
 137                 MOV     (mod3lo, acc)
 138                 MOV     (acc, i1)
 139                 SR      (acc)
 140                 SR      (acc)
 141                 SR      (acc)
 142                 OR      (mod3lo, acc)
 143                 CALL    (mod3)
 144                 ADD     (acc, n)
 145                 CALL    (g)
 146                 SR      (acc)
 147                 SR      (acc)
 148                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 149                 MOV     (acc, i2)
 150                 // shift-divide by six
 151                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
 152                 SR      (acc)
 153                 ADD     (acc, i2)
 154                 SR      (acc)
 155                 SR      (acc)
 156                 ADD     (acc, i2)
 157                 SR      (acc)
 158                 SR      (acc)
 159                 ADD     (acc, i2)
 160                 SR      (acc)
 161                 SR      (acc)
 162                 SR      (acc)
 163                 // end divide by six
 164                 AND     (acc, tmp_1) // acc restored from tmp_1
 165                 AND     (acc, 3)
 166                 ADD     (sample, acc)
 167
 168                 MOV     (acc, i2)
 169                 MOV     (mod3hi, acc)
 170                 SR      (mod3hi)
 171                 SR      (mod3hi)
 172                 SWAP    (acc)
 173                 AND     (acc, 0xf0)
 174                 SL      (acc)
 175                 SL      (acc)
 176                 MOV     (mod3lo, acc)
 177                 MOV     (acc, i1)
 178                 SR      (acc)
 179                 SR      (acc)
 180                 OR      (mod3lo, acc)
 181                 CALL    (mod3)
 182                 SUB     (acc, n)
 183                 SUB     (acc, 8)
 184                 NEG     (acc)
 185                 CALL    (g)
 186                 SR      (acc)
 187                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 188                 MOV     (acc, i2)
 189                 // shift-divide by ten
 190                 // note: i2 is max 0x78; so acc will <= 12.
 191                 INC     (i2)
 192                 SR      (acc)
 193                 ADD     (acc, i2)
 194                 SR      (acc)
 195                 SR      (acc)
 196                 SR      (acc)
 197                 ADD     (acc, i2)
 198                 SR      (acc)
 199                 ADD     (acc, i2)
 200                 SWAP    (acc)
 201                 DEC     (i2)
 202                 // end divide by ten
 203                 AND     (acc, tmp_1) // acc restored from tmp_1
 204                 AND     (acc, 3)
 205                 ADD     (sample, acc)
 206
 207                 MOV     (acc, sample)
 208                 SWAP    (acc)
 209                 putchar(acc);
 210
 211                 INC     (i0)
 212                 i1 += !i0; // ADDC i1
 213                 i2 += !i1 && !i0; // ADDC i2
 214
 215                 if(i2 == 0x78) break;
 216         }
 217 }