Add serial.fxf: Serial terminal

Makefile

@@ -23,6 +23,9 @@ base_image/barclock.fxf: applications/barclock/main.asm
 base_image/terminal.fxf: applications/terminal/main.asm $(wildcard applications/terminal/*.asm)
 	$(FOX32ASM) $< $@
 
+base_image/serial.fxf: applications/serial/main.asm $(wildcard applications/terminal/*.asm)
+	$(FOX32ASM) $< $@
+
 base_image/foxpaint.fxf: applications/foxpaint/main.asm
 	$(FOX32ASM) $< $@
 
@@ -53,6 +56,7 @@ FILES = \
 	base_image/sh.fxf \
 	base_image/barclock.fxf \
 	base_image/terminal.fxf \
+	base_image/serial.fxf \
 	base_image/foxpaint.fxf \
 	base_image/bg.fxf \
 	base_image/bg.raw \

applications/serial/main.asm

@@ -0,0 +1,61 @@
+; serial terminal - spawn sh.fxf on the serial port
+
+    ; start an instance of sh.fxf
+    call get_unused_task_id
+    mov.8 [shell_task_id], r0
+    mov r1, stream_struct
+    call new_shell_task
+
+event_loop:
+    movz.8 r0, [shell_task_id]
+    call is_task_id_used
+    ifz call end_current_task
+    call yield_task
+    rjmp event_loop
+
+print_str_to_terminal:
+    push r0
+    push r1
+print_str_to_terminal_loop:
+    mov r1, [r0]
+    cmp r1, 0
+    ifz jmp print_str_to_terminal_out
+    out 0, r1
+    inc r0
+    jmp print_str_to_terminal_loop
+print_str_to_terminal_out:
+    pop r1
+    pop r0
+
+stream_struct:
+    data.8  0x00
+    data.16 0x00
+    data.32 0x00
+    data.8  0x01
+    data.32 stream_read
+    data.32 stream_write
+
+shell_task_id: data.8 0
+
+stream_read:
+    in r0, 0
+    ret
+
+stream_write:
+    push r0
+    movz.8 r0, [r0]
+    bts r0, 7
+    ifnz jmp stream_write_special
+    out 0, r0
+    pop r0
+    ret
+stream_write_special:
+    cmp r0, 0x8a
+    ifz out 0, ' '
+    pop r0
+    ret
+
+
+#include "../terminal/task.asm"
+#include "../../../fox32rom/fox32rom.def"
+#include "../../fox32os.def"