1 files changed, 143 insertions, 0 deletions
diff --git a/riscv/htif.cc b/riscv/htif.cc
new file mode 100644
index 0000000..02809d0
--- /dev/null
+++ b/riscv/htif.cc
@@ -0,0 +1,143 @@
+#include "htif.h"
+#include "common.h"
+#include "sim.h"
+#include <unistd.h>
+#include <stdexcept>
+#include <stdlib.h>
+#include <errno.h>
+#include <assert.h>
+
+enum
+{
+  APP_CMD_READ_MEM,
+  APP_CMD_WRITE_MEM,
+  APP_CMD_READ_CONTROL_REG,
+  APP_CMD_WRITE_CONTROL_REG,
+  APP_CMD_START,
+  APP_CMD_STOP,
+  APP_CMD_ACK,
+  APP_CMD_NACK
+};
+
+#define APP_DATA_ALIGN 8
+#define APP_MAX_DATA_SIZE 1024
+struct packet
+{
+  uint16_t cmd;
+  uint16_t seqno;
+  uint32_t data_size;
+  uint64_t addr;
+  uint8_t  data[APP_MAX_DATA_SIZE];
+};
+
+htif_t::htif_t(int _tohost_fd, int _fromhost_fd)
+  : sim(NULL), tohost_fd(_tohost_fd), fromhost_fd(_fromhost_fd), seqno(1)
+{
+}
+
+htif_t::~htif_t()
+{
+  close(tohost_fd);
+  close(fromhost_fd);
+}
+
+void htif_t::init(sim_t* _sim)
+{
+  sim = _sim;
+}
+
+void htif_t::wait_for_start()
+{
+  while(wait_for_packet() != APP_CMD_START);
+}
+
+void htif_t::wait_for_fromhost_write()
+{
+  while(wait_for_packet() != APP_CMD_WRITE_CONTROL_REG);
+}
+
+void htif_t::send_packet(packet* p)
+{
+  int bytes = write(tohost_fd,p,offsetof(packet,data)+p->data_size);
+  if((size_t)bytes != offsetof(packet,data) + p->data_size)
+  {
+    const char* error = bytes == -1 ? strerror(errno) : "not all bytes sent";
+    fprintf(stderr,"HTIF error: %s\n", error);
+    exit(-1);
+  }
+}
+
+void htif_t::nack(uint16_t nack_seqno)
+{
+  packet p = {APP_CMD_NACK,nack_seqno,0,0};
+  send_packet(&p);
+}
+
+int htif_t::wait_for_packet()
+{
+  while(1)
+  {
+    packet p;
+    int bytes = read(fromhost_fd,&p,sizeof(p));
+    if(bytes < (int)offsetof(packet,data))
+    {
+      const char* error = bytes == -1 ? strerror(errno) : "too few bytes read";
+      fprintf(stderr,"HTIF error: %s\n", error);
+      exit(-1);
+    }
+  
+    if(p.seqno != seqno)
+    {
+      nack(p.seqno);
+      continue;
+    }
+
+    packet ackpacket = {APP_CMD_ACK,seqno,0,0};
+
+    switch(p.cmd)
+    {
+      case APP_CMD_START:
+        break;
+      case APP_CMD_STOP:
+        sim->stop();
+        break;
+      case APP_CMD_READ_MEM:
+        assert(p.addr % APP_DATA_ALIGN == 0);
+        assert(p.data_size % APP_DATA_ALIGN == 0);
+        assert(p.data_size <= APP_MAX_DATA_SIZE);
+        assert(p.addr <= sim->memsz && p.addr+p.data_size <= sim->memsz);
+        ackpacket.data_size = p.data_size;
+
+        static_assert(APP_DATA_ALIGN >= sizeof(uint64_t))
+        for(size_t i = 0; i < p.data_size/8; i++)
+          ((uint64_t*)ackpacket.data)[i] = sim->mmu->load_uint64(p.addr+i*8);
+        break;
+      case APP_CMD_WRITE_MEM:
+        assert(p.addr % APP_DATA_ALIGN == 0);
+        assert(p.data_size % APP_DATA_ALIGN == 0);
+        assert(p.data_size <= bytes - offsetof(packet,data));
+        assert(p.addr <= sim->memsz && p.addr+p.data_size <= sim->memsz);
+
+        for(size_t i = 0; i < p.data_size/8; i++)
+          sim->mmu->store_uint64(p.addr+i*8, ((uint64_t*)p.data)[i]);
+        break;
+      case APP_CMD_READ_CONTROL_REG:
+        assert(p.addr == 16);
+        assert(p.data_size == sizeof(reg_t));
+        ackpacket.data_size = sizeof(reg_t);
+        memcpy(ackpacket.data,&sim->tohost,sizeof(reg_t));
+        break;
+      case APP_CMD_WRITE_CONTROL_REG:
+        assert(p.addr == 17);
+        assert(p.data_size == sizeof(reg_t));
+        sim->tohost = 0;
+        memcpy(&sim->fromhost,p.data,sizeof(reg_t));
+        break;
+    }
+
+    send_packet(&ackpacket);
+    seqno++;
+    return p.cmd;
+  }
+}
+