Initial commit

main.c

@@ -0,0 +1,109 @@
+#include <stdint.h>
+#include "boot.h"
+#include "circ_buf.h"
+
+#define CPUREG 0x00
+#define CPUREG_ROM_DISABLE 0x01
+#define CPUREG_BANK_SELECT 0x02
+#define CPUREG_BANK_ENABLE 0x04
+#define CPUREG_GPO_0 0x08
+#define CPUREG_GPO_1 0x10
+#define CPUREG_GPO_2 0x20
+#define CPUREG_GPO_3 0x40
+#define CPUREG_GPO_4 0x80
+#define CPUREG_GPO_MASK 0xf8
+
+#define UART_CTC_CARD_BASE 0x20
+
+#define CTC_BASE (UART_CTC_CARD_BASE+0x00)
+#define CTC_CHANNEL_0 (CTC_BASE+0)
+#define CTC_CHANNEL_1 (CTC_BASE+1)
+#define CTC_CHANNEL_2 (CTC_BASE+2)
+#define CTC_CHANNEL_3 (CTC_BASE+3)
+
+#define UART_BASE (UART_CTC_CARD_BASE+0x04)
+#define UART_CONTROL (UART_BASE+0)
+#define UART_DATA (UART_BASE+1)
+
+volatile uint8_t v;
+volatile uint8_t uart_tx_busy;
+volatile circular_buffer_t rx_buf;
+volatile circular_buffer_t tx_buf;
+
+void uart_puts(char * c){
+    while(*c){
+        // fill tx buffer till it is full
+        while(*c && buffer_enqueue(&tx_buf, *c)){
+            c++;
+        }
+        // if uart not busy kick off
+        if(!uart_tx_busy){
+            disable_interrupts();
+            char cc;
+            if(buffer_dequeue(&tx_buf, &cc)){
+                uart_tx_busy = 1;
+                io_out(UART_DATA, cc);
+                io_out(UART_CONTROL, 0b10110101);
+            }
+            enable_interrupts();
+        }
+    }
+}
+
+void uart_interrupt(){
+    uint8_t status = io_in(UART_CONTROL);
+
+    if((status&0x21)!=0){
+        // RDRF or OVRN
+        char c = io_in(UART_DATA);
+        if((status&0x01)!=0){
+            // RDRF
+            buffer_enqueue(&rx_buf, c);
+        }
+    }
+
+    if((status&0x02)!=0 && uart_tx_busy){
+        //TXRE
+        char c;
+        if(buffer_dequeue(&tx_buf, &c)){
+            io_out(UART_DATA, c);
+        }else{
+            io_out(UART_CONTROL, 0b10010101);
+            uart_tx_busy = 0;
+        }
+    }
+}
+
+void ctc_interrupt(){
+}
+
+void main(){
+    buffer_init(&rx_buf);
+    buffer_init(&tx_buf);
+
+    io_out(CTC_CHANNEL_0, 0x57); // no int, counter @ rising, value follows, soft reset, control word
+    io_out(CTC_CHANNEL_0, 13); // 38.462 kHz out;
+
+    io_out(CTC_CHANNEL_3, 0b11001111); // int, counter @ falling, ext trig, value follows, soft reset, control word
+    io_out(CTC_CHANNEL_3, 1);
+
+    io_out(CTC_CHANNEL_0, 0x00); // vector follows
+    io_out(CTC_CHANNEL_0, 0x40);
+    
+    uart_tx_busy = 0;
+    io_out(UART_CONTROL, 0b00000011); // master reset
+    io_out(UART_CONTROL, 0b10010101); // recv int, 8N1, /16 -> 2403.85 baud
+    
+    enable_interrupts();
+
+    uart_puts("Z80 monitor - v1\r\n");
+    uart_puts("----------------\r\n");
+
+    v = 0;
+    for(;;){
+        char c[2] = {0, 0};
+        while(buffer_dequeue(&rx_buf, c)){
+            uart_puts(c);
+        }
+    }
+}