riscv/applink.cc

   1 #include "applink.h"
   2 #include "common.h"
   3 #include "sim.h"
   4 #include <unistd.h>
   5 #include <stdexcept>
   6
   7 enum
   8 {
   9   APP_CMD_READ_MEM,
  10   APP_CMD_WRITE_MEM,
  11   APP_CMD_READ_CONTROL_REG,
  12   APP_CMD_WRITE_CONTROL_REG,
  13   APP_CMD_START,
  14   APP_CMD_STOP,
  15   APP_CMD_ACK,
  16   APP_CMD_NACK
  17 };
  18
  19 #define APP_DATA_ALIGN 8
  20 #define APP_MAX_DATA_SIZE 1024
  21 struct packet
  22 {
  23   uint16_t cmd;
  24   uint16_t seqno;
  25   uint32_t data_size;
  26   uint64_t addr;
  27   uint8_t  data[APP_MAX_DATA_SIZE];
  28 };
  29
  30 class packet_error : public std::runtime_error
  31 {
  32 public:
  33   packet_error(const std::string& s) : std::runtime_error(s) {}
  34 };
  35 class io_error : public packet_error
  36 {
  37 public:
  38   io_error(const std::string& s) : packet_error(s) {}
  39 };
  40
  41 appserver_link_t::appserver_link_t(int _tohost_fd, int _fromhost_fd)
  42   : sim(NULL), tohost_fd(_tohost_fd), fromhost_fd(_fromhost_fd), seqno(1)
  43 {
  44 }
  45
  46 void appserver_link_t::init(sim_t* _sim)
  47 {
  48   sim = _sim;
  49 }
  50
  51 void appserver_link_t::wait_for_start()
  52 {
  53   while(wait_for_packet() != APP_CMD_START);
  54 }
  55
  56 void appserver_link_t::send_packet(packet* p)
  57 {
  58   while(1) try
  59   {
  60     int bytes = write(tohost_fd,p,offsetof(packet,data)+p->data_size);
  61     if(bytes == -1 || (size_t)bytes != offsetof(packet,data)+p->data_size)
  62       throw io_error("write failed");
  63     return;
  64   }
  65   catch(io_error e)
  66   {
  67     fprintf(stderr,"warning: %s\n",e.what());
  68   }
  69 }
  70
  71 void appserver_link_t::nack(uint16_t nack_seqno)
  72 {
  73   packet p = {APP_CMD_NACK,nack_seqno,0,0};
  74   send_packet(&p);
  75 }
  76
  77 int appserver_link_t::wait_for_packet()
  78 {
  79   while(1) try
  80   {
  81     packet p;
  82     int bytes = read(fromhost_fd,&p,sizeof(p));
  83     if(bytes < (signed)offsetof(packet,data))
  84       throw io_error("read failed");
  85
  86     if(p.seqno != seqno)
  87     {
  88       nack(p.seqno);
  89       continue;
  90     }
  91
  92     packet ackpacket = {APP_CMD_ACK,seqno,0,0};
  93
  94     switch(p.cmd)
  95     {
  96       case APP_CMD_START:
  97         break;
  98       case APP_CMD_STOP:
  99         send_packet(&ackpacket);
 100         exit(0);
 101       case APP_CMD_READ_MEM:
 102         demand(p.addr % APP_DATA_ALIGN == 0, "misaligned address");
 103         demand(p.data_size % APP_DATA_ALIGN == 0, "misaligned data");
 104         demand(p.data_size <= APP_MAX_DATA_SIZE, "long read data");
 105         demand(p.addr <= sim->memsz && p.addr+p.data_size <= sim->memsz, "out of bounds");
 106         memcpy(ackpacket.data,sim->mem+p.addr,p.data_size);
 107         ackpacket.data_size = p.data_size;
 108         break;
 109       case APP_CMD_WRITE_MEM:
 110         demand(p.addr % APP_DATA_ALIGN == 0, "misaligned address");
 111         demand(p.data_size % APP_DATA_ALIGN == 0, "misaligned data");
 112         demand(p.data_size <= bytes - offsetof(packet,data), "short packet");
 113         demand(p.addr <= sim->memsz && p.addr+p.data_size <= sim->memsz, "out of bounds");
 114         memcpy(sim->mem+p.addr,p.data,p.data_size);
 115         break;
 116       case APP_CMD_READ_CONTROL_REG:
 117         demand(p.addr == 16,"bad control reg");
 118         demand(p.data_size == sizeof(reg_t),"bad control reg size");
 119         ackpacket.data_size = sizeof(reg_t);
 120         memcpy(ackpacket.data,&sim->tohost,sizeof(reg_t));
 121         break;
 122       case APP_CMD_WRITE_CONTROL_REG:
 123         demand(p.addr == 17,"bad control reg");
 124         demand(p.data_size == sizeof(reg_t),"bad control reg size");
 125         sim->tohost = 0;
 126         memcpy(&sim->fromhost,p.data,sizeof(reg_t));
 127         break;
 128     }
 129
 130     send_packet(&ackpacket);
 131     seqno++;
 132     return p.cmd;
 133   }
 134   catch(io_error e)
 135   {
 136     fprintf(stderr,"warning: %s\n",e.what());
 137   }
 138 }
 139