Added Uart support

Author: visrealm

src/CMakeLists.txt

@@ -11,7 +11,7 @@ target_sources(${PROGRAM} PRIVATE main.c bus.c rom.c)
 pico_add_extra_outputs(${PROGRAM})
 
 pico_enable_stdio_usb(${PROGRAM} 1)
-pico_enable_stdio_uart(${PROGRAM} 1)
+pico_enable_stdio_uart(${PROGRAM} 0)
 
 target_link_libraries(${PROGRAM} PRIVATE
         pico-56-tms9918

src/boot-menu/boot-menu.c

@@ -306,6 +306,8 @@ void runBootMenu()
     vrEmuTms9918WriteString(tms9918, "Loading ");
     vrEmuTms9918WriteString(tms9918, fileList[currentIndex].fname);
 
+    printf("Loading %s...\n", fileList[currentIndex].fname);
+
     FIL fil;
     fr = f_open(&fil, fileList[currentIndex].fname, FA_OPEN_EXISTING | FA_READ);
     if (fr == FR_OK || fr == FR_EXIST)

src/bus.c

@@ -26,6 +26,7 @@
 #include "pico/time.h"
 
 #include <stdlib.h>
+#include <stdio.h>
 
  // HBC-56 RAM
 static uint8_t __aligned(4) ram[HBC56_RAM_SIZE];
@@ -60,6 +61,14 @@ FIL fil;
 
 #define CPU_6502_WAI 0xcb
 
+#define UART_STATUS_RX_REG_FULL       0b00000001
+#define UART_STATUS_TX_REG_EMPTY      0b00000010
+
+static uint8_t uartControl = 0;
+static uint8_t uartStatus = UART_STATUS_TX_REG_EMPTY;
+static uint8_t uartBuffer = 0;
+
+
 /*
  * 65c02 bus read/write callbacks
  */
@@ -160,6 +169,7 @@ void __not_in_flash_func(busMainLoop)()
 
   absolute_time_t startTime = get_absolute_time();
   absolute_time_t currentTime = startTime;
+  absolute_time_t nextUartTime = startTime;
 
   int i = 0;
   int prevViaInt = IntCleared;
@@ -183,6 +193,26 @@ void __not_in_flash_func(busMainLoop)()
     // run the via for a number of ticks
     vrEmu6522Ticks(via, TICKS_PER_BURST);
 
+    if (uartBuffer == 0)
+    {
+      nextUartTime = delayed_by_us(currentTime, 100);
+      int c = getchar_timeout_us(0);
+      if (c != PICO_ERROR_TIMEOUT)
+      {
+        //        putchar(c);
+        uartBuffer = c;// & 0xff;
+        raiseInterrupt(HBC56_UART_IRQ);
+        uartStatus = UART_STATUS_TX_REG_EMPTY;
+        uartStatus |= UART_STATUS_RX_REG_FULL;
+      }
+      else
+      {
+        releaseInterrupt(HBC56_UART_IRQ);
+        uartStatus &= ~(UART_STATUS_RX_REG_FULL);
+      }
+    }
+
+
     // has the via interrupted?
     setOrClearInterrupt(HBC56_VIA_IRQ, *vrEmu6522Int(via) == IntRequested);
 
@@ -202,6 +232,7 @@ void __not_in_flash_func(busMainLoop)()
   }
 }
 
+
 /*
  * 65c02 write to the bus
  */
@@ -243,6 +274,22 @@ void __not_in_flash_func(busWrite)(uint16_t addr, uint8_t val)
           audioWritePsg1(addr, val);
           break;
 
+        case HBC56_UART_PORT:
+          uartControl = val;
+          if ((val & 0x03) == 0x03)   // reset
+          {
+            uartStatus = UART_STATUS_TX_REG_EMPTY;
+          }
+          else
+          {
+            releaseInterrupt(HBC56_UART_IRQ);
+          }
+          break;
+
+        case HBC56_UART_PORT | 0x01:
+          putchar(val);
+          break;
+
         case FOPEN_PORT:
           {
             uint16_t addr = ram[val] | (ram[val + 1] << 8);
@@ -341,6 +388,23 @@ uint8_t __not_in_flash_func(busRead)(uint16_t addr, bool isDbg)
         case HBC56_AY38910_B_PORT | 0x02:
           return audioReadPsg1();
 
+        case HBC56_UART_PORT:
+          return uartStatus;
+
+        case HBC56_UART_PORT | 0x01:
+          {
+            int c = getchar_timeout_us(0);
+            if (c == PICO_ERROR_TIMEOUT)
+            {
+              releaseInterrupt(HBC56_UART_IRQ);
+              uartStatus &= ~(UART_STATUS_RX_REG_FULL);
+              c = 0;
+            }
+            uint8_t val = uartBuffer;
+            uartBuffer = c;
+            return val;
+          }
+
         case FCLOSE_PORT:
           f_close(&fil);
           return 0;

src/config.h

@@ -67,11 +67,11 @@
 
 #ifdef _WINDOWS
 #define HBC56_HAVE_UART         1
+#endif
 #define HBC56_UART_PORT         0x20
 #define HBC56_UART_PORTNAME     "COM7"
 #define HBC56_UART_CLOCK_FREQ   HBC56_CLOCK_FREQ
 #define HBC56_UART_IRQ          3
-#endif
 
 /* computed configuration values (shouldn't need to touch these) 
   -------------------------------------------------------------------------- */

src/devices/interrupts/interrupts.c

@@ -21,7 +21,7 @@ void setOrClearInterrupt(int irq, bool doSet)
 
 void raiseInterrupt(int irq)
 {
-  interruptRegister |= 1 << (irq - 1);
+  interruptRegister |= (1 << (irq - 1));
 }
 
 void releaseInterrupt(int irq)