Supply UEFI module path as environment variable

We'd like to have multiple backends -- e.g. Linux instead of UEFI. That would
make testing less cumbersome.

Also remove an outdated comment.

diff --git a/Makefile b/Makefile
index ff474b0b073405bea8aa8a32171a7cdda2fbd61a..362c429255dcef90992572cfe584f70047864f6c 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -14,9 +14,9 @@ OVMF_CODE.fd: /usr/share/ovmf/x64/OVMF_CODE.fd
 OVMF_VARS.fd: /usr/share/ovmf/x64/OVMF_VARS.fd
        cp $< $@
 
-out/main: main.asm impl.asm bootstrap.asm sys.f uefi.asm
+out/main: main.asm impl.asm bootstrap.asm sys.f os/uefi.asm
        mkdir -p out
-       fasm $< out/main
+       OS_INCLUDE=os/uefi.asm fasm $< $@
 
 .PHONY: clean
 clean:

diff --git a/main.asm b/main.asm
index 43eef7a7e52ab27a253ad343ec775ae83e0a8b22..0190d18ae34525e0cb67aa3bb7e29827f484efa7 100644 (file)
--- a/main.asm
+++ b/main.asm
@@ -1,18 +1,6 @@
 ;; vim: syntax=fasm
 
-include "uefi.asm"
-
-;; "Syscalls" {{{
-
-;; [NOTE] Volatile registers Linux (syscalls) vs UEFI
-;;
-;;   Linux syscalls: RAX, RCX, R11
-;;   UEFI:           RAX, RCX, R11, RDX, R8, R9, R10
-
-;; We are in the process of replacing our dependency on Linux with a dependency
-;; on UEFI. The following macros attempt to isolate what would be syscalls in
-;; Linux; thus, we will be able to replace these with UEFI-based implementations,
-;; and in theory we should expect the program to work.
+include '%OS_INCLUDE%'
 
 ;; Print a string of a given length.
 ;;
@@ -64,8 +52,6 @@ macro sys_terminate code {
   call uefi_terminate
 }
 
-;; }}}
-
 ;; The code in this macro is placed at the end of each Forth word. When we are
 ;; executing a definition, this code is what causes execution to resume at the
 ;; next word in that definition.

diff --git a/os/uefi.asm b/os/uefi.asm
new file mode 100644 (file)
index 0000000..d116b2c
--- /dev/null
+++ b/os/uefi.asm
@@ -0,0 +1,192 @@
+;; vim: syntax=fasm
+
+format pe64 dll efi
+entry main
+
+;; EFI struct definitions {{{
+
+EFI_NOT_READY = 0x8000_0000_0000_0000 or 6
+
+;; Based on https://wiki.osdev.org/Uefi.inc
+macro struct name {
+  virtual at 0
+    name name
+  end virtual
+}
+
+struc EFI_TABLE_HEADER {
+  dq ?
+  dd ?
+  dd ?
+  dd ?
+  dd ?
+}
+
+struc EFI_SYSTEM_TABLE {
+  .Hdr EFI_TABLE_HEADER
+  .FirmwareVendor dq ? ; CHAR16*
+  .FirmwareRevision dd ? ; UINT32
+  align 8
+  .ConsoleInHandle dq ? ; EFI_HANDLE
+  .ConIn dq ? ; EFI_SIMPLE_TEXT_INPUT_PROTOCOL*
+  .ConsoleOutHandle dq ? ; EFI_HANDLE
+  .ConOut dq ? ; EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL*
+  ; ...
+}
+struct EFI_SYSTEM_TABLE
+
+struc EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL {
+  .Reset dq ? ; EFI_TEXT_RESET
+  .OutputString dq ? ; EFI_TEXT_STRING
+  ; ...
+}
+struct EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
+
+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
+
+uefi_initialize:
+  ; At program startup, RDX contains an EFI_SYSTEM_TABLE*.
+  mov [system_table], rdx
+  ret
+
+;; Print a string of the given length.
+;;
+;; Inputs:
+;;  - RCX = String buffer
+;;  - RDX = String length
+uefi_print_string:
+  ;; We take an input string of bytes without any terminator. We need to turn
+  ;; this string into a string of words, terminated by a null character.
+
+  mov rdi, .output_buffer ; Current location in output string
+
+.copy_byte:
+  ;; When there are no characters left in the input string, we are done.
+  cmp rdx, 0
+  je .done
+
+  ;; Load byte from input string
+  mov al, byte [rcx]
+
+  ;; Copy byte to output string
+
+  cmp al, $A
+  jne .not_newline
+.newline:
+  ;; It's a newline; replace it with '\r\n' in output string.
+  mov byte [rdi], $D
+  inc rdi
+  mov byte [rdi], 0
+  inc rdi
+  mov byte [rdi], $A
+  inc rdi
+  mov byte [rdi], 0
+  inc rdi
+  jmp .pop
+
+.not_newline:
+  ;; Not a newline, proceed as normal:
+  mov byte [rdi], al
+  inc rdi
+
+  ;; The output string has words rather than bytes for charactesr, so we need
+  ;; to add an extra zero:
+  mov byte [rdi], 0
+  inc rdi
+
+.pop:
+  ;; We finished copying character to output string, so pop it from the input
+  ;; string.
+  inc rcx
+  dec rdx
+
+  jmp .copy_byte
+.done:
+  ;; Append a final null-word:
+  mov word [rdi], 0
+
+  ; At this point we have our null-terminated word-string at .output_buffer. Now
+  ; we just need to print it.
+
+  mov rcx, [system_table]                                       ; EFI_SYSTEM_TABLE* rcx
+  mov rcx, [rcx + EFI_SYSTEM_TABLE.ConOut]                      ; EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL* rcx
+  mov rdx, .output_buffer
+  mov rbx, [rcx + EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.OutputString] ; EFI_TEXT_STRING rbx
+  sub rsp, 32
+  call rbx
+  add rsp, 32
+  ret
+
+;; Read a character as an ASCII byte into the given buffer.
+;;
+;; Inputs:
+;; - RCX = Character buffer (1 byte)
+uefi_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
+
+  ;; Special handling of enter (UEFI gives us '\r', but we want '\n'.)
+  cmp ax, $D
+  jne .no_enter
+  mov byte [r15], $A
+.no_enter:
+
+  ;; Print the character
+  mov rcx, r15
+  mov rdx, 1
+  call uefi_print_string
+
+  ret
+
+;; Terminate with the given error code.
+;;
+;; Inputs:
+;; - RCX = Error code
+uefi_terminate:
+  mov rcx, terminated_msg
+  mov rdx, terminated_msg.len
+  call uefi_print_string
+  jmp $
+
+section '.data' readable writable
+
+system_table dq ? ; EFI_SYSTEM_TABLE*
+
+terminated_msg db 0xD, 0xA, '(The program has terminated.)', 0xD, 0xA
+.len = $ - terminated_msg
+
+uefi_print_string.output_buffer rq 0x400
+
+char_buffer db ?
+
+input_key EFI_INPUT_KEY

diff --git a/uefi.asm b/uefi.asm
deleted file mode 100644 (file)
index d116b2c..0000000
--- a/uefi.asm
+++ /dev/null
@@ -1,192 +0,0 @@
-;; vim: syntax=fasm
-
-format pe64 dll efi
-entry main
-
-;; EFI struct definitions {{{
-
-EFI_NOT_READY = 0x8000_0000_0000_0000 or 6
-
-;; Based on https://wiki.osdev.org/Uefi.inc
-macro struct name {
-  virtual at 0
-    name name
-  end virtual
-}
-
-struc EFI_TABLE_HEADER {
-  dq ?
-  dd ?
-  dd ?
-  dd ?
-  dd ?
-}
-
-struc EFI_SYSTEM_TABLE {
-  .Hdr EFI_TABLE_HEADER
-  .FirmwareVendor dq ? ; CHAR16*
-  .FirmwareRevision dd ? ; UINT32
-  align 8
-  .ConsoleInHandle dq ? ; EFI_HANDLE
-  .ConIn dq ? ; EFI_SIMPLE_TEXT_INPUT_PROTOCOL*
-  .ConsoleOutHandle dq ? ; EFI_HANDLE
-  .ConOut dq ? ; EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL*
-  ; ...
-}
-struct EFI_SYSTEM_TABLE
-
-struc EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL {
-  .Reset dq ? ; EFI_TEXT_RESET
-  .OutputString dq ? ; EFI_TEXT_STRING
-  ; ...
-}
-struct EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL
-
-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
-
-uefi_initialize:
-  ; At program startup, RDX contains an EFI_SYSTEM_TABLE*.
-  mov [system_table], rdx
-  ret
-
-;; Print a string of the given length.
-;;
-;; Inputs:
-;;  - RCX = String buffer
-;;  - RDX = String length
-uefi_print_string:
-  ;; We take an input string of bytes without any terminator. We need to turn
-  ;; this string into a string of words, terminated by a null character.
-
-  mov rdi, .output_buffer ; Current location in output string
-
-.copy_byte:
-  ;; When there are no characters left in the input string, we are done.
-  cmp rdx, 0
-  je .done
-
-  ;; Load byte from input string
-  mov al, byte [rcx]
-
-  ;; Copy byte to output string
-
-  cmp al, $A
-  jne .not_newline
-.newline:
-  ;; It's a newline; replace it with '\r\n' in output string.
-  mov byte [rdi], $D
-  inc rdi
-  mov byte [rdi], 0
-  inc rdi
-  mov byte [rdi], $A
-  inc rdi
-  mov byte [rdi], 0
-  inc rdi
-  jmp .pop
-
-.not_newline:
-  ;; Not a newline, proceed as normal:
-  mov byte [rdi], al
-  inc rdi
-
-  ;; The output string has words rather than bytes for charactesr, so we need
-  ;; to add an extra zero:
-  mov byte [rdi], 0
-  inc rdi
-
-.pop:
-  ;; We finished copying character to output string, so pop it from the input
-  ;; string.
-  inc rcx
-  dec rdx
-
-  jmp .copy_byte
-.done:
-  ;; Append a final null-word:
-  mov word [rdi], 0
-
-  ; At this point we have our null-terminated word-string at .output_buffer. Now
-  ; we just need to print it.
-
-  mov rcx, [system_table]                                       ; EFI_SYSTEM_TABLE* rcx
-  mov rcx, [rcx + EFI_SYSTEM_TABLE.ConOut]                      ; EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL* rcx
-  mov rdx, .output_buffer
-  mov rbx, [rcx + EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.OutputString] ; EFI_TEXT_STRING rbx
-  sub rsp, 32
-  call rbx
-  add rsp, 32
-  ret
-
-;; Read a character as an ASCII byte into the given buffer.
-;;
-;; Inputs:
-;; - RCX = Character buffer (1 byte)
-uefi_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
-
-  ;; Special handling of enter (UEFI gives us '\r', but we want '\n'.)
-  cmp ax, $D
-  jne .no_enter
-  mov byte [r15], $A
-.no_enter:
-
-  ;; Print the character
-  mov rcx, r15
-  mov rdx, 1
-  call uefi_print_string
-
-  ret
-
-;; Terminate with the given error code.
-;;
-;; Inputs:
-;; - RCX = Error code
-uefi_terminate:
-  mov rcx, terminated_msg
-  mov rdx, terminated_msg.len
-  call uefi_print_string
-  jmp $
-
-section '.data' readable writable
-
-system_table dq ? ; EFI_SYSTEM_TABLE*
-
-terminated_msg db 0xD, 0xA, '(The program has terminated.)', 0xD, 0xA
-.len = $ - terminated_msg
-
-uefi_print_string.output_buffer rq 0x400
-
-char_buffer db ?
-
-input_key EFI_INPUT_KEY