;; - [X] Print a string of a given length
;; - [ ] Print a single character
;; - [ ] Terminate the program (? - What should this do?)
-;; - [ ] Read a single character
+;; - [X] Read a single character
;; - This should allow the user to type in a string, and then feed the
;; buffer to us one character at a time.
+;; - [ ] We want to show the user's input on the screen while reading
+;; - [ ] Read a file that was bundled with the program
+;; - It looks like we can use EFI_LOAD_FILE_PROTOCOL.LoadFile() to load
+;; a file into a buffer. In order to be able to use this, we need to
+;; have some way of interpreting a static buffer instead of reading as
+;; we go.
-;; #region Structs
+;; EFI struct definitions {{{
+
+EFI_NOT_READY = 0x8000_0000_0000_0000 or 6
;; Based on https://wiki.osdev.org/Uefi.inc
macro struct name {
}
struct EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
-;; #endregion
+struc EFI_SIMPLE_TEXT_INPUT_PROTOCOL {
+ .Reset dq ? ; EFI_INPUT_RESET
+ .ReadKeyStroke dq ? ; EFI_INPUT_READ_KEY
+ ; ...
+}
+struct EFI_SIMPLE_TEXT_INPUT_PROTOCOL
+
+struc EFI_INPUT_KEY {
+ .ScanCode dw ? ; UINT16
+ .UnicodeChar dw ? ; CHAR16
+ align 8
+}
+struct EFI_INPUT_KEY
+
+;; }}}
section '.text' code executable readable
mov rdx, hello_string.len
call print_string
- mov rcx, hello_string
- mov rdx, hello_string.len
+ mov rcx, char_buffer
+ call read_char
+
+ mov rcx, char_buffer
+ mov rdx, 1
call print_string
mov rcx, hello_string
add rsp, 32
ret
+;; Read a character as an ASCII byte into the given buffer.
+;;
+;; Inputs:
+;; - RCX = Character buffer (1 byte)
+read_char:
+ mov r15, rcx
+.read_key:
+ mov rcx, [system_table] ; EFI_SYSTEM_TABLE* rcx
+ mov rcx, [rcx + EFI_SYSTEM_TABLE.ConIn] ; EFI_SIMPLE_TEXT_INPUT_PROTOCOL* rcx
+ mov rbx, [rcx + EFI_SIMPLE_TEXT_INPUT_PROTOCOL.ReadKeyStroke] ; EFI_INPUT_READ_KEY rbx
+ mov rdx, input_key ; EFI_INPUT_KEY* rdx
+ sub rsp, 32
+ call rbx
+ add rsp, 32
+
+ mov r8, EFI_NOT_READY
+ cmp rax, r8
+ je .read_key
+
+ mov ax, [input_key.UnicodeChar]
+ mov [r15], al
+
+ ret
+
section '.data' readable writable
system_table dq ? ; EFI_SYSTEM_TABLE*
.len = $ - hello_string
print_string.output_buffer rq 0x400
+
+char_buffer db ?
+
+input_key EFI_INPUT_KEY