continuing with serial driver in dsa.

dsa_resources/serial.dsa

@@ -1,57 +1,74 @@
-dw uart: 0x40000
-// ------------------------------------------
-// reads up to rg1 bytes into buffer at rg2
-// args: buf_size @ bpr+8, buf_addr @ bpr+12
-// returns: 0 in bpr+8 on success, 1 on nullptr error
-buf_read: func
-    push rg0
-    push rg1
-    push rg2
-    push rg3
-    ldw bpr, rg1, 8         // buf size
-    ldw bpr, rg2, 12        // buf addr
-    jez rg2, _buf_read_err  // return err if nullptr
-_buf_read_loop:
-    jez rg1, _buf_read_end
-    call read_byte
-    ldw bpr, rg3, 8         // read return value from frame
-    stb rg3, rg2            // store into buffer
-    addi rg2, 1, rg2
-    subi rg1, 1, rg1
-    jmp _buf_read_loop
-_buf_read_end:
-    stw zero, bpr, 8        // return 0 (success)
-    pop rg3
-    pop rg2
-    pop rg1
-    pop rg0
-    return
-_buf_read_err:
-    lli 1, rg0
-    stw rg0, bpr, 8         // return 1 (error)
-    pop rg3
-    pop rg2
-    pop rg1
-    pop rg0
+// Serial port address in MMIO
+dw UART: 0x40000
+
+// Reserve space for our read buffer
+resb SERIAL_BUFFER: 1024
+dw SER_READ_PTR: 0
+dw SER_WRITE_PTR: 0
+
+serial_init: func
+    lwi SERIAL_BUFFER, rg0
+    stw rg0, SER_READ_PTR, 0	
+	stw rg0, SER_WRITE_PTR, 0
     return
 
+serial_isr: 
+	push rg0
+	push rg1
+	push rg2
+
+    ldw UART, rg0
+    ldb rg0, rg1, 2 // load ser_in_valid flag
+
+    // no serial input
+    jez rg1, _serial_isr_end
+
+    // we should have a valid byte to read at offset 3
+    ldb rg0, rg1, 3 // data byte
+
+	// write data to ptr and increment
+    ldw SER_WRITE_PTR, rg2
+	stb rg1, rg2
+	addi rg2, 1
+
+	// load buff+1024
+    lwi SERIAL_BUFFER, rg0
+	addi rg0, 1024, rg1
+
+	// if ptr != buff+1024, nowrap.
+	ine rg1, rg2, rg1
+	jnz rg1, _serial_isr_nowrap
+
+	lwi SERIAL_BUFFER, rg2 // set the pointer
+
+_serial_isr_nowrap:
+    stw rg2, SER_WRITE_PTR
+
+_serial_isr_end:
+	pop rg0
+	pop rg1
+	pop rg2
+    iret
+
+
+
 // read_byte: emulator → kernel
 // reads data from base+0x00, valid flag at base+0x01
 read_byte: func
     push rg0
     push rg1
     push rg2
-    ldw uart, rg1
+    ldw UART, rg1
 _serial_read_wait:
-    ldb rg1, rg0, 1         // base+0x01 = read valid flag
+    ldb rg1, rg0, 2         // base+0x02 = read valid flag
     lli 0x01, rg2
     ieq rg0, rg2, rg2
     jnz rg2, _serial_read_ready
     hlt
     jmp _serial_read_wait
 _serial_read_ready:
-    ldb rg1, rg0, 0         // base+0x00 = data byte
-    stb zero, rg1, 1        // clear read valid flag
+    ldb rg1, rg0, 3         // base+0x03 = data byte
+    stb zero, rg1, 2        // clear read valid flag
     stb rg0, bpr, 8         // return byte
     pop rg2
     pop rg1
@@ -59,22 +76,22 @@ _serial_read_ready:
     return
 
 // _serial_send: kernel → emulator
-// writes data to base+0x02, valid flag to base+0x03
+// writes data to base+0x01, valid flag to base+0x00
 _serial_send:
     push rg0
     push rg2
     push rg3
     push rg4
     push rg5
-    ldw uart, rg5
+    ldw UART, rg5
 _serial_wait:
-    ldb rg5, rg2, 3         // base+0x03 = write valid flag
+    ldb rg5, rg2, 0         // base+0x00 = ser_out_valid
     lli 0x01, rg3
     ieq rg2, rg3, rg4
     jnz rg4, _serial_wait   // wait while emulator hasn't consumed yet
-    stb rg0, rg5, 2         // base+0x02 = data byte
+    stb rg0, rg5, 1         // base+0x01 = ser_out_data
     lli 0x01, rg2
-    stb rg2, rg5, 3         // base+0x03 = set valid flag
+    stb rg2, rg5, 0         // base+0x00 = ser_out_valid = 1
     pop rg5
     pop rg4
     pop rg3
@@ -114,3 +131,39 @@ print_byte: func
 // ------------------------------------------
 _serial_end:
     return
+
+// ------------------------------------------
+// reads up to rg1 bytes into buffer at rg2
+// args: buf_size @ bpr+8, buf_addr @ bpr+12
+// returns: 0 in bpr+8 on success, 1 on nullptr error
+buf_read: func
+    push rg0
+    push rg1
+    push rg2
+    push rg3
+    ldw bpr, rg1, 8         // buf size
+    ldw bpr, rg2, 12        // buf addr
+    jez rg2, _buf_read_err  // return err if nullptr
+_buf_read_loop:
+    jez rg1, _buf_read_end
+    call read_byte
+    ldw bpr, rg3, 8         // read return value from frame
+    stb rg3, rg2            // store into buffer
+    addi rg2, 1, rg2
+    subi rg1, 1, rg1
+    jmp _buf_read_loop
+_buf_read_end:
+    stw zero, bpr, 8        // return 0 (success)
+    pop rg3
+    pop rg2
+    pop rg1
+    pop rg0
+    return
+_buf_read_err:
+    lli 1, rg0
+    stw rg0, bpr, 8         // return 1 (error)
+    pop rg3
+    pop rg2
+    pop rg1
+    pop rg0
+    return