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         /*T0SN  FLAG.C (0x00.1)*/       if (flag_c){ // skip if carry clear
  44         ADD (acc,3)                     }
  45 }
  46
  47 void g(void){
  48         // notes_ix_hi = always 0
  49         u8 notes_ix;//lo
  50         AND     (acc, 0x7)
  51         MOV     (notes_ix, acc)
  52         // test i2 & 3:
  53         MOV     (acc, i2)
  54         AND     (acc, 3)
  55         /*T0SN  FLAG.Z (0x00.0)*/       if(3&i2) {// skip if !(3&i0)
  56         SET1    (notes_ix, 3)           } // ix += 8 <=> ix |= 8
  57         IDXM    (acc, notes+notes_ix)
  58         u8 result = ((i1<<8|i0)*acc)>>8;  // keep hi byte
  59         //^TODO! https://git.gir.st/Chiptunes.git/blob/d397f89:/foo.c#l83
  60         //final: https://git.gir.st/Chiptunes.git/blob/f8e0502:/foo.S#l113
  61         u8 a2 = 0; // can probably be overloaded onto mul3lo/hi
  62         u8 a1 = 0; // -"-
  63         u8 t  = acc; // note input (as returned by idxm)
  64         for (u8 loop = 0; loop < 8; loop++) {
  65                 SR      (t)
  66                 /*T1SN  FLAG.C (0x00.1)*/       if (!flag_c) // skip if carry set
  67                 goto skip;
  68                 MOV     (acc, i0)
  69                 ADD     (a1, acc)
  70                 MOV     (acc, i1)
  71                 ADDC    (a2, acc)
  72         skip:   SR      (a2)
  73                 SRC     (a1)
  74         }
  75         acc = a1;
  76 }
  77 void main(void){
  78         CLEAR   (i0)
  79         CLEAR   (i1)
  80         CLEAR   (i2)
  81
  82         //rom is not mmapped; must load into ram first
  83         MOV     (acc, 0x84)
  84         MOV     (notes[0x0], acc)
  85         MOV     (notes[0x5], acc)
  86         MOV     (acc, 0x9d)
  87         MOV     (notes[0x1], acc)
  88         MOV     (notes[0x4], acc)
  89         MOV     (acc, 0xb0)
  90         MOV     (notes[0x2], acc)
  91         MOV     (notes[0xA], acc)
  92         MOV     (acc, 0x69)
  93         MOV     (notes[0x3], acc)
  94         MOV     (notes[0x6], acc)
  95         MOV     (notes[0xB], acc)
  96         MOV     (notes[0xE], acc)
  97         MOV     (acc, 0x58)
  98         MOV     (notes[0x7], acc)
  99         MOV     (notes[0xF], acc)
 100         MOV     (acc, 0x75)
 101         MOV     (notes[0x8], acc)
 102         MOV     (notes[0xD], acc)
 103         MOV     (acc, 0x8c)
 104         MOV     (notes[0x9], acc)
 105         MOV     (notes[0xC], acc)
 106
 107         for(;;) {
 108                 MOV     (acc, i2)// "mov mem,mem"
 109                 MOV     (n, acc)// does not exist
 110                 SL      (n)
 111                 SL      (n)
 112                 MOV     (acc, i1)
 113                 SWAP    (acc)
 114                 AND     (acc, 0xf)
 115                 SR      (acc)
 116                 SR      (acc)
 117                 OR      (n, acc)
 118
 119                 MOV     (acc, n)
 120                 CALL    (g)
 121                 SWAP    (acc)
 122                 AND     (acc, 0x1)
 123                 MOV     (sample, acc)
 124
 125                 MOV     (acc, i2)
 126                 SL      (acc)
 127                 SL      (acc)
 128                 SL      (acc)
 129                 MOV     (tmp_1, acc) // fresh tmp_1:
 130                 MOV     (acc, i1)
 131                 SWAP    (acc)
 132                 AND     (acc, 0xf)
 133                 SR      (acc)
 134                 OR      (acc, tmp_1) // tmp_1 done.
 135                 XOR     (acc, n)
 136                 CALL    (g)
 137                 SR      (acc)
 138                 AND     (acc, i2)
 139                 SR      (acc)
 140                 AND     (acc, 3)
 141                 ADD     (sample, acc)
 142
 143                 MOV     (acc, i2)
 144                 MOV     (mod3hi, acc)
 145                 SR      (mod3hi)
 146                 SR      (mod3hi)
 147                 SR      (mod3hi)
 148                 SWAP    (acc)
 149                 AND     (acc, 0xf0)
 150                 SL      (acc)
 151                 MOV     (mod3lo, acc)
 152                 MOV     (acc, i1)
 153                 SR      (acc)
 154                 SR      (acc)
 155                 SR      (acc)
 156                 OR      (mod3lo, acc)
 157                 CALL    (mod3)
 158                 ADD     (acc, n)
 159                 CALL    (g)
 160                 SR      (acc)
 161                 SR      (acc)
 162                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 163                 MOV     (acc, i2)
 164                 // shift-divide by six
 165                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
 166                 SR      (acc)
 167                 ADD     (acc, i2)
 168                 SR      (acc)
 169                 SR      (acc)
 170                 ADD     (acc, i2)
 171                 SR      (acc)
 172                 SR      (acc)
 173                 ADD     (acc, i2)
 174                 SR      (acc)
 175                 SR      (acc)
 176                 SR      (acc)
 177                 // end divide by six
 178                 AND     (acc, tmp_1) // acc restored from tmp_1
 179                 AND     (acc, 3)
 180                 ADD     (sample, acc)
 181
 182                 MOV     (acc, i2)
 183                 MOV     (mod3hi, acc)
 184                 SR      (mod3hi)
 185                 SR      (mod3hi)
 186                 SWAP    (acc)
 187                 AND     (acc, 0xf0)
 188                 SL      (acc)
 189                 SL      (acc)
 190                 MOV     (mod3lo, acc)
 191                 MOV     (acc, i1)
 192                 SR      (acc)
 193                 SR      (acc)
 194                 OR      (mod3lo, acc)
 195                 CALL    (mod3)
 196                 SUB     (acc, n)
 197                 SUB     (acc, 8)
 198                 NEG     (acc)
 199                 CALL    (g)
 200                 SR      (acc)
 201                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 202                 MOV     (acc, i2)
 203                 // shift-divide by ten
 204                 // note: i2 is max 0x78; so acc will <= 12.
 205                 INC     (i2)
 206                 SR      (acc)
 207                 ADD     (acc, i2)
 208                 SR      (acc)
 209                 SR      (acc)
 210                 SR      (acc)
 211                 ADD     (acc, i2)
 212                 SR      (acc)
 213                 ADD     (acc, i2)
 214                 SWAP    (acc)
 215                 DEC     (i2)
 216                 // end divide by ten
 217                 AND     (acc, tmp_1) // acc restored from tmp_1
 218                 AND     (acc, 3)
 219                 ADD     (sample, acc)
 220
 221                 MOV     (acc, sample)
 222                 SWAP    (acc)
 223                 putchar(acc);
 224
 225                 INC     (i0)
 226                 /*ADDC  i1*/            i1 += !i0;
 227                 /*ADDC  i2*/            i2 += !i1 && !i0;
 228
 229                 if(i2 == 0x78) break;
 230         }
 231 }