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 u8 xmod3(u8,u8);
  18 void mod3(void) {
  19         acc = xmod3(mod3hi, mod3lo);
  20 }
  21
  22 u8 xmod3(u8 hi, u8 lo) { //avail: t, o _
  23 //copied from attiny version e98ab46; based on homepage.divms.uiowa.edu/~jones
  24     unsigned short a = ((hi) + (lo)) &0x1ff;
  25         hi = a>>8; //1 bit
  26         lo = a;
  27     lo = (hi<<4|lo>>4) + (lo & 0xF);
  28     lo = (lo >>  2) + (lo & 0x3);
  29     lo = (lo >>  2) + (lo & 0x3);
  30     if (lo > 2) lo = lo - 3;
  31     return lo;
  32 }
  33
  34
  35 void g(void){
  36         u8 notes_ix = acc & 0x7;
  37         if(3&i2)
  38                 notes_ix += 8;
  39         u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
  40         acc = result;
  41 }
  42 void main(void){
  43         CLEAR   (i0)
  44         CLEAR   (i1)
  45         CLEAR   (i2)
  46         for(;;) {
  47                 MOV     (acc, i2)// "mov mem,mem"
  48                 MOV     (n, acc)// does not exist
  49                 SL      (n)
  50                 SL      (n)
  51                 MOV     (acc, i1)
  52                 SWAP    (acc)
  53                 AND     (acc, 0xf)
  54                 SR      (acc)
  55                 SR      (acc)
  56                 OR      (n, acc)
  57
  58                 MOV     (acc, n)
  59                 CALL    (g)
  60                 SWAP    (acc)
  61                 AND     (acc, 0x1)
  62                 MOV     (sample, acc)
  63
  64                 MOV     (acc, i2)
  65                 SL      (acc)
  66                 SL      (acc)
  67                 SL      (acc)
  68                 MOV     (tmp_1, acc) // fresh tmp_1:
  69                 MOV     (acc, i1)
  70                 SWAP    (acc)
  71                 AND     (acc, 0xf)
  72                 SR      (acc)
  73                 OR      (acc, tmp_1) // tmp_1 done.
  74                 XOR     (acc, n)
  75                 CALL    (g)
  76                 SR      (acc)
  77                 AND     (acc, i2)
  78                 SR      (acc)
  79                 AND     (acc, 3)
  80                 ADD     (sample, acc)
  81
  82                 mod3hi = i2>>3;
  83                 mod3lo = i2<<5|i1>>3;
  84                 CALL    (mod3)
  85                 ADD     (acc, n)
  86                 CALL    (g)
  87                 SR      (acc)
  88                 SR      (acc)
  89                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
  90                 MOV     (acc, i2)
  91                 // shift-divide by six
  92                 // note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
  93                 SR      (acc)
  94                 ADD     (acc, i2)
  95                 SR      (acc)
  96                 SR      (acc)
  97                 ADD     (acc, i2)
  98                 SR      (acc)
  99                 SR      (acc)
 100                 ADD     (acc, i2)
 101                 SR      (acc)
 102                 SR      (acc)
 103                 SR      (acc)
 104                 // end divide by six
 105                 AND     (acc, tmp_1) // acc restored from tmp_1
 106                 AND     (acc, 3)
 107                 ADD     (sample, acc)
 108
 109                 mod3hi = i2>>2;
 110                 mod3lo = i2<<6|i1>>2;
 111                 CALL    (mod3)
 112                 SUB     (acc, n)
 113                 SUB     (acc, 8)
 114                 NEG     (acc)
 115                 CALL    (g)
 116                 SR      (acc)
 117                 MOV     (tmp_1, acc) // acc saved in tmp_1; fresh acc
 118                 MOV     (acc, i2)
 119                 // shift-divide by ten
 120                 // note: i2 is max 0x78; so acc will <= 12.
 121                 INC     (i2)
 122                 SR      (acc)
 123                 ADD     (acc, i2)
 124                 SR      (acc)
 125                 SR      (acc)
 126                 SR      (acc)
 127                 ADD     (acc, i2)
 128                 SR      (acc)
 129                 ADD     (acc, i2)
 130                 SWAP    (acc)
 131                 DEC     (i2)
 132                 // end divide by ten
 133                 AND     (acc, tmp_1) // acc restored from tmp_1
 134                 AND     (acc, 3)
 135                 ADD     (sample, acc)
 136
 137                 MOV     (acc, sample)
 138                 SWAP    (acc)
 139                 putchar(acc);
 140
 141                 INC     (i0)
 142                 i1 += !i0; // ADDC i1
 143                 i2 += !i1 && !i0; // ADDC i2
 144         }
 145 }