dbdma: introduce new DMA API.

devices/common/dbdma.cpp

@@ -102,6 +102,7 @@ uint8_t DMAChannel::interpret_cmd() {
                 break;
             case DBDMA_Cmd::INPUT_MORE:
             case DBDMA_Cmd::INPUT_LAST:
+                this->xfer_from_device();
                 if (this->in_cb)
                     this->in_cb();
                 break;
@@ -406,6 +407,20 @@ void DMAChannel::reg_write(uint32_t offset, uint32_t value, int size) {
     }
 }
 
+void DMAChannel::xfer_from_device() {
+    if (this->dev_obj == nullptr)
+        return;
+
+    this->xfer_dir = DMA_DIR_FROM_DEV;
+
+    if (!this->dev_obj->xfer_from(this->queue_data, this->queue_len)) {
+        this->queue_len = 0;
+        this->finish_cmd();
+    }
+
+    this->interpret_cmd();
+}
+
 DmaPullResult DMAChannel::pull_data(uint32_t req_len, uint32_t *avail_len, uint8_t **p_data)
 {
     *avail_len = 0;

devices/common/dbdma.h

@@ -103,7 +103,7 @@ namespace DBDMA_Cmd {
 
 typedef std::function<void(void)> DbdmaCallback;
 
-class DMAChannel : public DmaBidirChannel {
+class DMAChannel : public DmaBidirChannel, public DmaChannel {
 public:
     DMAChannel(std::string name) : DmaBidirChannel(name) {}
     ~DMAChannel() = default;
@@ -134,6 +134,7 @@ protected:
     void finish_cmd();
     void xfer_quad(const DMACmd *cmd_desc, DMACmd *cmd_host);
     void update_irq();
+    void xfer_from_device();
 
     void start(void);
     void resume(void);

devices/common/dmacore.h

@@ -1,6 +1,6 @@
 /*
 DingusPPC - The Experimental PowerPC Macintosh emulator
-Copyright (C) 2018-22 divingkatae and maximum
+Copyright (C) 2018-24 divingkatae and maximum
                       (theweirdo)     spatium
 
 (Contact divingkatae#1017 or powermax#2286 on Discord for more info)
@@ -25,6 +25,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #define DMA_CORE_H
 
 #include <cstdint>
+#include <cinttypes>
 #include <string>
 
 enum DmaPullResult : int {
@@ -75,4 +76,52 @@ private:
     std::string name;
 };
 
+// ---------------------- New DMA API -------------------------
+enum DmaMsg : unsigned {
+    CH_START    = 1,
+    CH_STOP,
+    DATA_AVAIL,
+};
+
+enum XferDir : unsigned {
+    DMA_DIR_UNDEF       = 0,
+    DMA_DIR_TO_DEV,
+    DMA_DIR_FROM_DEV,
+};
+
+class DmaChannel;
+
+class DmaDevice {
+public:
+    DmaDevice()  = default;
+    ~DmaDevice() = default;
+
+    void connect(DmaChannel *ch_obj) { this->channel_obj = ch_obj; };
+    void notify(DmaMsg msg) {};
+    virtual int xfer_from(uint8_t *buf, int len) { return len; };
+
+protected:
+    DmaChannel* channel_obj = nullptr;
+};
+
+class DmaChannel {
+public:
+    DmaChannel()  = default;
+    ~DmaChannel() = default;
+
+    void connect(DmaDevice *dev_obj) { this->dev_obj = dev_obj; };
+    void notify(DmaMsg msg) {};
+
+protected:
+    DmaDevice*  dev_obj  = nullptr;
+    XferDir     xfer_dir = DMA_DIR_UNDEF;
+};
+
+/*
+    TODO: write CONNECT macro that
+    - constructs both DmaChannel and DmaDevice objects
+    - calls connect() method on both objects
+    - initializes DMA interrupts
+*/
+
 #endif // DMA_CORE_H