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                 mod3hi = i2>>3;
  99                 MOV(acc, i2)
 100                 SWAP(acc)
 101                 AND(acc, 0xf0)
 102                 SL(acc)
 103                 MOV(mod3lo, acc)
 104                 MOV(acc, i1)
 105                 SR(acc)
 106                 SR(acc)
 107                 SR(acc)
 108                 OR(mod3lo, acc)
 109                 CALL    (mod3)
 110                 ADD     (acc, n)
 111                 CALL    (g)
 112                 SR      (acc)
 113                 SR      (acc)
 114                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 115                 MOV     (acc, i2)
 116                 // shift-divide by six
 117                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
 118                 SR      (acc)
 119                 ADD     (acc, i2)
 120                 SR      (acc)
 121                 SR      (acc)
 122                 ADD     (acc, i2)
 123                 SR      (acc)
 124                 SR      (acc)
 125                 ADD     (acc, i2)
 126                 SR      (acc)
 127                 SR      (acc)
 128                 SR      (acc)
 129                 // end divide by six
 130                 AND     (acc, tmp_1) // acc restored from tmp_1
 131                 AND     (acc, 3)
 132                 ADD     (sample, acc)
 133
 134                 mod3hi = i2>>2;
 135                 mod3lo = i2<<6|i1>>2;
 136                 CALL    (mod3)
 137                 SUB     (acc, n)
 138                 SUB     (acc, 8)
 139                 NEG     (acc)
 140                 CALL    (g)
 141                 SR      (acc)
 142                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 143                 MOV     (acc, i2)
 144                 // shift-divide by ten
 145                 // note: i2 is max 0x78; so acc will <= 12.
 146                 INC     (i2)
 147                 SR      (acc)
 148                 ADD     (acc, i2)
 149                 SR      (acc)
 150                 SR      (acc)
 151                 SR      (acc)
 152                 ADD     (acc, i2)
 153                 SR      (acc)
 154                 ADD     (acc, i2)
 155                 SWAP    (acc)
 156                 DEC     (i2)
 157                 // end divide by ten
 158                 AND     (acc, tmp_1) // acc restored from tmp_1
 159                 AND     (acc, 3)
 160                 ADD     (sample, acc)
 161
 162                 MOV     (acc, sample)
 163                 SWAP    (acc)
 164                 putchar(acc);
 165
 166                 INC     (i0)
 167                 i1 += !i0; // ADDC i1
 168                 i2 += !i1 && !i0; // ADDC i2
 169
 170                 if(i2 == 0x78) break;
 171         }
 172 }