ROM2/coinmech.c

   1 #include "coinmech.h"
   2 #include "vend.h"
   3
   4 #define COINMECH_ID   0x20
   5
   6 u8 last_byte;
   7 u8 packet_pos = 0;
   8 u16 value_1 = 0;
   9 u8 value_2 = 0;
  10 u8 dec_point = 0;
  11
  12 u16 coin_value = 0;
  13 u8 item_cost = 0;
  14 bool have_change = 0;
  15
  16 u8 parity_test(u8 c) {
  17         u8 parity = 0;
  18         for (parity = 0; c; c = c>>1) {
  19                 if (c&1) parity = !parity;
  20         }
  21         return parity;
  22 }
  23
  24 bool parity_good(u8 c) {
  25
  26 /*
  27  * parity_good truth table:
  28  *
  29  *      | parity_test(c)
  30  *      | 0   1
  31  * -----+---------
  32  * R8 0 | 1   0
  33  *    1 | 0   1
  34  */
  35
  36         u8 R8 = (_io_ports[M6811_SCCR1] & M6811_R8)?1:0;
  37         u8 p = parity_test(c)?1:0;
  38         return R8 == p;
  39 }
  40
  41 void send_byte(u8 c) {
  42         last_byte = c;
  43         while (!(_io_ports[M6811_SCSR] & M6811_TDRE)); /* wait for TD register empty */
  44
  45         if (parity_test(c))
  46                 bset((void*)&_io_ports[M6811_SCCR1], M6811_T8);
  47         else
  48                 bclr((void*)&_io_ports[M6811_SCCR1], M6811_T8);
  49 }
  50
  51 void ask_for_retrans() {
  52         /* sends an 0xff down the line */
  53         send_byte(0xff);
  54 }
  55
  56
  57 #define IS_CTRL(x) (x & 0x10) /* true if this packet is a control packet */
  58 void sci_interrupt() {
  59         u8 in;
  60         in = _io_ports[M6811_SCDR];
  61
  62         /* test for framing errors & parity bit */
  63         if (_io_ports[M6811_SCSR] & M6811_FE || !parity_good(in)) {
  64                 _io_ports[M6811_SCDR]; /* read of register req'd to clear FE */
  65                 ask_for_retrans();
  66                 return;
  67         }
  68
  69         /* all bytes must have the correct ID in the 3 MSBs */
  70         if ((in & 0xe0) != COINMECH_ID) return;
  71
  72         /* we have a good packet */
  73         if (in == 0x3f) {
  74                 /* retransmit was requested */
  75                 send_byte(last_byte);
  76                 return;
  77         }
  78
  79         if (packet_pos != 0 || IS_CTRL(in&0x10)) {
  80                 in &= 0x0f;
  81                 switch (in) {
  82                         case 0x01:
  83                                 /* just reply with ack */
  84                                 /* original firmware does something with link master price holding */
  85                                 send_byte(0x00);
  86                         case 0x02:
  87                                 /* write back how much change to give, or 0xfe to hold it. */
  88                                 if (item_cost) {
  89                                         send_byte(item_cost / value_2);
  90                                 } else
  91                                         send_byte(0xfe);
  92                                 break;
  93                         case 0x03:
  94                                 /* hmmm, maybe we're sposed to do something here. firmware doesnt */
  95                                 /* and just sets a random bit - something like "changer in use"?  */
  96                                 break;
  97                         case 0x08:
  98                                 /* start of packet */
  99                                 packet_pos = 1;
 100                                 send_byte(0x00);
 101                                 break;
 102                         default:
 103                                 /* just ack it and move on */
 104                                 send_byte(0x00);
 105                 }
 106         } else {
 107                 in &= 0x0f;
 108                 switch (packet_pos) {
 109                         case 1: value_1  = in;           break;
 110                         case 2: value_1 |= in << 4;      break;
 111                         case 3: value_1 |= in << 8;      break;
 112                         case 4: value_1 |= in << 12;     break;
 113                         case 5: value_2  = in;           break;
 114                         case 6: value_2 |= in << 4;      break;
 115                         case 7: dec_point = in;          break;
 116                         case 8: have_change = (in&0x01); break;
 117                         default:
 118                                         if (packet_pos == 9) {
 119                                                 packet_pos = 0;
 120                                                 coin_value = value_1*value_2;
 121                                         }
 122                                         /* hmmm, else? */
 123                 }
 124                 packet_pos++;
 125                 send_byte(0x00); /* ack */
 126         }
 127 }
 128
 129 void coin_eat() {
 130         coin_cost(coin_value); /* eat everything */
 131 }
 132
 133 void coin_cost(u16 cost) {
 134         item_cost = cost;
 135 }