foo.c

   1 #include <stdio.h>
   2 #include "fakeasm.h"
   3 typedef unsigned char u8;
   4
   5 u8 data[] = {
   6         0x84, 0x9d, 0xb0, 0x69, 0x9d, 0x84, 0x69, 0x58,
   7         0x75, 0x8c, 0xb0, 0x69, 0x8c, 0x75, 0x69, 0x58
   8 };
   9 u8 i0;
  10 u8 i1;
  11 u8 i2;
  12 u8 i3;
  13 u8 x;
  14 u8 t;
  15 u8 o;
  16 void g(void) {
  17         // g(i, x, t, o) -> t
  18         u8 tmp;
  19         ANDI    (t, 0x07)
  20         MOV     (tmp, i2)
  21         ANDI    (tmp, 3)
  22         TST     (tmp)
  23         BREQ    (skip)
  24         SUBI    (t, -8)
  25         skip:
  26         t = data[t];
  27         t = (((i1&0x1f)<<8|i0)*t)>>8 >> o;
  28         AND     (t, x)
  29         ANDI    (t, 3)
  30         RET
  31 };
  32
  33 int main(void) {
  34         u8 n;
  35         u8 s;
  36         u8 acc;
  37         //TODO: clear all vars/registers
  38         for (;;) {
  39                 MOV     (n, i2)
  40                 LSL     (n)
  41                 LSL     (n)
  42                 #define tmp acc
  43                 MOV     (tmp, i1)
  44                 SWAP    (tmp)
  45                 ANDI    (tmp, 0x0f)
  46                 LSR     (tmp)
  47                 LSR     (tmp)
  48                 OR      (n, tmp)
  49                 #undef tmp
  50                 MOV     (s, i3)
  51                 ROR     (s)
  52                 ROR     (s)
  53                 ANDI    (s, 0x80)
  54                 #define tmp acc
  55                 MOV     (tmp, i2)
  56                 LSR     (tmp)
  57                 OR      (s, tmp)
  58                 #undef tmp
  59
  60                 //voice 1:
  61                 LDI     (x, 1)
  62                 MOV     (t, n)
  63                 LDI     (o, 4)
  64                 RCALL   g();
  65                 MOV     (acc, t)
  66
  67                 //voice 2:
  68                 MOV     (x, s)
  69                 #define tmp o
  70                 MOV     (tmp, i2)
  71                 LSL     (tmp)
  72                 LSL     (tmp)
  73                 LSL     (tmp)
  74                 MOV     (t, i1)
  75                 SWAP    (t)
  76                 ANDI    (t, 0xf)
  77                 LSR     (t)
  78                 OR      (t, tmp)
  79                 #undef tmp
  80                 EOR     (t, n)
  81                 LDI     (o, 2)
  82                 RCALL   g();
  83                 ADD     (acc, t)
  84
  85                 //voice 3:
  86                 MOV     (x, s)
  87                 INC     (x)
  88                 #define tmp o
  89                 //NOTE: we only need 1 bit of the upper byte. instead of using a u16 and LSR'ing,
  90                 //we can use a u8 for sum and use ROR (which shifts the carry in)
  91                 CLR     (tmp)
  92                 ADD     (tmp, x)
  93                 ROR     (tmp)
  94                 //nop
  95                 LSR     (tmp)
  96                 ADD     (tmp, x)
  97                 ROR     (tmp)
  98                 //nop
  99                 LSR     (tmp)
 100                 ADD     (tmp, x)
 101                 ROR     (tmp)
 102                 //nop
 103                 LSR     (tmp)
 104                 ADD     (tmp, x)
 105                 ROR     (tmp)
 106                 //nop
 107                 LSR     (tmp)
 108                 x = tmp;
 109                 #undef tmp
 110                 t = ((i3&0x01)<<13 | i2<<5 | i1>>3) % 3;
 111                 ADD     (t, n)
 112                 LDI     (o, 2)
 113                 RCALL   g();
 114                 ADD     (acc, t)
 115
 116                 //voice 4:
 117                 MOV     (x, s)
 118                 INC     (x)
 119                 #define tmp o
 120                 unsigned short sum = 0; //XXX
 121                 sum += x;
 122                 sum >>= 1;
 123                 sum += x;
 124                 sum >>= 1;
 125                 //nop
 126                 sum >>= 1;
 127                 //nop
 128                 sum >>= 1;
 129                 sum += x;
 130                 sum >>= 1;
 131                 sum += x;
 132                 sum >>= 1;
 133                 //nop
 134                 sum >>= 1;
 135                 //nop
 136                 sum >>= 1;
 137                 x = sum;
 138                 #undef tmp
 139                 t = ((i3&0x01)<<14 | i2<<6 | i1>>2) % 3;
 140                 SUB     (t, n)
 141                 NEG     (t)
 142                 SUBI    (t, -8)
 143                 LDI     (o, 1)
 144                 RCALL   g();
 145                 ADD     (acc, t)
 146
 147                 putchar(acc<<4);
 148                 #define tmp acc
 149                 LDI     (tmp, 0)
 150                 SUBI    (i0, -1)
 151                 ADC     (i1, tmp, !i0)
 152                 ADC     (i2, tmp, !i0&&!i1)
 153                 ADC     (i3, tmp, !i0&&!i1&&!i2)
 154                 #undef tmp
 155         }
 156 }