scsi_bus: packet data transfers.

devices/common/scsi/sc53c94.h

@@ -144,6 +144,7 @@ public:
 
     // ScsiDevice methods
     void notify(ScsiBus* bus_obj, ScsiMsg msg_type, int param);
+    bool has_data() { return this->data_fifo_pos != 0; };
     bool send_bytes(uint8_t* dst_ptr, int count);
     void process_command() {};
 

devices/common/scsi/scsi.h

@@ -46,7 +46,7 @@ enum {
 };
 
 namespace ScsiPhase {
-enum : int {
+    enum : int {
         BUS_FREE = 0,
         ARBITRATION,
         SELECTION,
@@ -58,7 +58,7 @@ enum : int {
         MESSAGE_IN,
         MESSAGE_OUT,
         RESET,
-};
+    };
 };
 
 enum ScsiMsg : int {
@@ -140,6 +140,7 @@ public:
 
     virtual void notify(ScsiBus* bus_obj, ScsiMsg msg_type, int param);
 
+    virtual bool has_data() = 0;
     virtual bool send_bytes(uint8_t* dst_ptr, int count) = 0;
 
     virtual void process_command() = 0;
@@ -179,6 +180,8 @@ public:
     bool end_selection(int initiator_id, int target_id);
     bool transfer_command(uint8_t* dst_ptr);
     void disconnect(int dev_id);
+    bool target_request_data();
+    bool target_pull_data(uint8_t* dst_ptr, int size);
 
 protected:
     void change_bus_phase(int initiator_id);

devices/common/scsi/scsi_bus.cpp

@@ -246,6 +246,31 @@ bool ScsiBus::transfer_command(uint8_t* dst_ptr)
     return true;
 }
 
+bool ScsiBus::target_request_data()
+{
+    if (this->devices[this->target_id]->has_data()) {
+        this->assert_ctrl_line(target_id, SCSI_CTRL_REQ);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+bool ScsiBus::target_pull_data(uint8_t* dst_ptr, int size)
+{
+    if (dst_ptr == nullptr || !size) {
+        return false;
+    }
+
+    // transfer the requested number of bytes from target to initiator
+    if (!this->devices[this->target_id]->send_bytes(dst_ptr, size)) {
+        LOG_F(ERROR, "ScsiBus: error while transferring data from target!");
+        return false;
+    }
+
+    return true;
+}
+
 void ScsiBus::disconnect(int dev_id)
 {
     this->release_ctrl_lines(dev_id);

devices/common/scsi/scsi_hd.cpp

@@ -123,6 +123,18 @@ void ScsiHardDisk::process_command() {
     }
 }
 
+bool ScsiHardDisk::send_bytes(uint8_t* dst_ptr, int count) {
+    if (dst_ptr == nullptr || !count || count > this->cur_buf_cnt) {
+        return false;
+    }
+
+    std::memcpy(dst_ptr, &this->img_buffer[this->cur_buf_pos], count);
+    this->cur_buf_pos += count;
+    this->cur_buf_cnt -= count;
+
+    return true;
+}
+
 int ScsiHardDisk::test_unit_ready() {
     if (img_path.empty() || img_path == " ") {
         return ScsiError::DEV_NOT_READY;
@@ -204,6 +216,8 @@ void ScsiHardDisk::read(uint32_t lba, uint16_t transfer_len, uint8_t cmd_len) {
 
     this->hdd_img.seekg(device_offset, this->hdd_img.beg);
     this->hdd_img.read(img_buffer, transfer_size);
+
+    this->cur_buf_cnt = transfer_size;
 }
 
 void ScsiHardDisk::write(uint32_t lba, uint16_t transfer_len, uint8_t cmd_len) {

devices/common/scsi/scsi_hd.h

@@ -41,7 +41,8 @@ public:
     
     void insert_image(std::string filename);
     void process_command();
-    bool send_bytes(uint8_t* dst_ptr, int count) { return true; };
+    bool has_data() { return this->cur_buf_cnt != 0; };
+    bool send_bytes(uint8_t* dst_ptr, int count);
 
     int test_unit_ready();
     int req_sense(uint16_t alloc_len);
@@ -57,7 +58,7 @@ public:
     void seek(uint32_t lba);
     void rewind();
 
-protected:
+private:
     std::string img_path;
     std::fstream hdd_img;
     uint64_t img_size;
@@ -65,6 +66,10 @@ protected:
     uint64_t file_offset = 0;
     uint8_t status       = ScsiError::NO_ERROR;
 
+    // SCSI transfer pointers
+    uint32_t    cur_buf_pos = 0;
+    uint32_t    cur_buf_cnt = 0;
+
     //inquiry info
     char vendor_info[8] = {'D', 'i', 'n', 'g', 'u', 's', 'D', '\0'};
     char prod_info[16]  = {'E', 'm', 'u', 'l', 'a', 't', 'e', 'd', ' ', 'D', 'i', 's', 'k', '\0'};