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         SUB     (acc,3)
  47         if (flag_c){ // T0SN FLAG.C (0x00.1) -- skip if carry clear
  48                 ADD (acc,3)
  49         }
  50 }
  51
  52 void g(void){
  53         u8 notes_ix = acc & 0x7;
  54         if(3&i2)
  55                 notes_ix += 8;
  56         u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
  57         acc = result;
  58 }
  59 void main(void){
  60         CLEAR   (i0)
  61         CLEAR   (i1)
  62         CLEAR   (i2)
  63         for(;;) {
  64                 MOV     (acc, i2)// "mov mem,mem"
  65                 MOV     (n, acc)// does not exist
  66                 SL      (n)
  67                 SL      (n)
  68                 MOV     (acc, i1)
  69                 SWAP    (acc)
  70                 AND     (acc, 0xf)
  71                 SR      (acc)
  72                 SR      (acc)
  73                 OR      (n, acc)
  74
  75                 MOV     (acc, n)
  76                 CALL    (g)
  77                 SWAP    (acc)
  78                 AND     (acc, 0x1)
  79                 MOV     (sample, acc)
  80
  81                 MOV     (acc, i2)
  82                 SL      (acc)
  83                 SL      (acc)
  84                 SL      (acc)
  85                 MOV     (tmp_1, acc) // fresh tmp_1:
  86                 MOV     (acc, i1)
  87                 SWAP    (acc)
  88                 AND     (acc, 0xf)
  89                 SR      (acc)
  90                 OR      (acc, tmp_1) // tmp_1 done.
  91                 XOR     (acc, n)
  92                 CALL    (g)
  93                 SR      (acc)
  94                 AND     (acc, i2)
  95                 SR      (acc)
  96                 AND     (acc, 3)
  97                 ADD     (sample, acc)
  98
  99                 MOV     (acc, i2)
 100                 MOV     (mod3hi, acc)
 101                 SR      (mod3hi)
 102                 SR      (mod3hi)
 103                 SR      (mod3hi)
 104                 SWAP    (acc)
 105                 AND     (acc, 0xf0)
 106                 SL      (acc)
 107                 MOV     (mod3lo, acc)
 108                 MOV     (acc, i1)
 109                 SR      (acc)
 110                 SR      (acc)
 111                 SR      (acc)
 112                 OR      (mod3lo, acc)
 113                 CALL    (mod3)
 114                 ADD     (acc, n)
 115                 CALL    (g)
 116                 SR      (acc)
 117                 SR      (acc)
 118                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 119                 MOV     (acc, i2)
 120                 // shift-divide by six
 121                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
 122                 SR      (acc)
 123                 ADD     (acc, i2)
 124                 SR      (acc)
 125                 SR      (acc)
 126                 ADD     (acc, i2)
 127                 SR      (acc)
 128                 SR      (acc)
 129                 ADD     (acc, i2)
 130                 SR      (acc)
 131                 SR      (acc)
 132                 SR      (acc)
 133                 // end divide by six
 134                 AND     (acc, tmp_1) // acc restored from tmp_1
 135                 AND     (acc, 3)
 136                 ADD     (sample, acc)
 137
 138                 MOV     (acc, i2)
 139                 MOV     (mod3hi, acc)
 140                 SR      (mod3hi)
 141                 SR      (mod3hi)
 142                 SWAP    (acc)
 143                 AND     (acc, 0xf0)
 144                 SL      (acc)
 145                 SL      (acc)
 146                 MOV     (mod3lo, acc)
 147                 MOV     (acc, i1)
 148                 SR      (acc)
 149                 SR      (acc)
 150                 OR      (mod3lo, acc)
 151                 CALL    (mod3)
 152                 SUB     (acc, n)
 153                 SUB     (acc, 8)
 154                 NEG     (acc)
 155                 CALL    (g)
 156                 SR      (acc)
 157                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 158                 MOV     (acc, i2)
 159                 // shift-divide by ten
 160                 // note: i2 is max 0x78; so acc will <= 12.
 161                 INC     (i2)
 162                 SR      (acc)
 163                 ADD     (acc, i2)
 164                 SR      (acc)
 165                 SR      (acc)
 166                 SR      (acc)
 167                 ADD     (acc, i2)
 168                 SR      (acc)
 169                 ADD     (acc, i2)
 170                 SWAP    (acc)
 171                 DEC     (i2)
 172                 // end divide by ten
 173                 AND     (acc, tmp_1) // acc restored from tmp_1
 174                 AND     (acc, 3)
 175                 ADD     (sample, acc)
 176
 177                 MOV     (acc, sample)
 178                 SWAP    (acc)
 179                 putchar(acc);
 180
 181                 INC     (i0)
 182                 i1 += !i0; // ADDC i1
 183                 i2 += !i1 && !i0; // ADDC i2
 184
 185                 if(i2 == 0x78) break;
 186         }
 187 }