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;
  17 void mod3(void) {
  18         acc = (mod3hi<<8|mod3lo) % 3;
  19 }
  20
  21 void g(void){
  22         u8 notes_ix = acc & 0x7;
  23         if(3&i2)
  24                 notes_ix += 8;
  25         u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
  26         acc = result;
  27 }
  28 void main(void){
  29         CLEAR   (i0)
  30         CLEAR   (i1)
  31         CLEAR   (i2)
  32         for(;;) {
  33                 MOV     (acc, i2)// "mov mem,mem"
  34                 MOV     (n, acc)// does not exist
  35                 SL      (n)
  36                 SL      (n)
  37                 MOV     (acc, i1)
  38                 SWAP    (acc)
  39                 AND     (acc, 0xf)
  40                 SR      (acc)
  41                 SR      (acc)
  42                 OR      (n, acc)
  43
  44                 MOV     (acc, n)
  45                 CALL    (g)
  46                 SWAP    (acc)
  47                 AND     (acc, 0x1)
  48                 MOV     (sample, acc)
  49
  50                 MOV     (acc, i2)
  51                 SL      (acc)
  52                 SL      (acc)
  53                 SL      (acc)
  54                 MOV     (tmp_1, acc) // fresh tmp_1:
  55                 MOV     (acc, i1)
  56                 SWAP    (acc)
  57                 AND     (acc, 0xf)
  58                 SR      (acc)
  59                 OR      (acc, tmp_1) // tmp_1 done.
  60                 XOR     (acc, n)
  61                 CALL    (g)
  62                 SR      (acc)
  63                 AND     (acc, i2)
  64                 SR      (acc)
  65                 AND     (acc, 3)
  66                 ADD     (sample, acc)
  67
  68                 mod3hi = i2>>3;
  69                 mod3lo = i2<<5|i1>>3;
  70                 mod3();
  71                 ADD     (acc, n)
  72                 CALL    (g)
  73                 SR      (acc)
  74                 SR      (acc)
  75                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
  76                 MOV     (acc, i2)
  77                 // shift-divide by six
  78                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
  79                 SR      (acc)
  80                 ADD     (acc, i2)
  81                 SR      (acc)
  82                 SR      (acc)
  83                 ADD     (acc, i2)
  84                 SR      (acc)
  85                 SR      (acc)
  86                 ADD     (acc, i2)
  87                 SR      (acc)
  88                 SR      (acc)
  89                 SR      (acc)
  90                 // end divide by six
  91                 AND     (acc, tmp_1) // acc restored from tmp_1
  92                 AND     (acc, 3)
  93                 ADD     (sample, acc)
  94
  95                 MOV     (acc, n)
  96                 ADD     (acc, 8)
  97                 { u8 tmp3 = ((i2<<6|i1>>2)&0x1fff)%3;
  98                   SUB   (acc, tmp3)
  99                 } // tmp3
 100                 CALL    (g)
 101                 SR      (acc)
 102                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 103                 MOV     (acc, i2)
 104                 // shift-divide by ten
 105                 // note: i2 is max 0x78; so acc will <= 12.
 106                 INC     (i2)
 107                 SR      (acc)
 108                 ADD     (acc, i2)
 109                 SR      (acc)
 110                 SR      (acc)
 111                 SR      (acc)
 112                 ADD     (acc, i2)
 113                 SR      (acc)
 114                 ADD     (acc, i2)
 115                 SWAP    (acc)
 116                 DEC     (i2)
 117                 // end divide by ten
 118                 AND     (acc, tmp_1) // acc restored from tmp_1
 119                 AND     (acc, 3)
 120                 ADD     (sample, acc)
 121
 122                 MOV     (acc, sample)
 123                 SWAP    (acc)
 124                 putchar(acc);
 125
 126                 INC     (i0)
 127                 i1 += !i0; // ADDC i1
 128                 i2 += !i1 && !i0; // ADDC i2
 129         }
 130 }