From: Jonas Hvid <mail@johv.dk>
Date: Sun, 4 Oct 2020 00:14:04 +0000 (+0200)
Subject: Add placeholder implementation of Linux backend
X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=5224cfbc1856cd2f4c786f73223b1182acbc96cc;p=rrq%2Fjonasforth.git

Add placeholder implementation of Linux backend
---

diff --git a/.gitignore b/.gitignore
index 5557c76..cef3077 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 /out
+/main
 /OVMF_CODE.fd
 /OVMF_VARS.fd
diff --git a/Makefile b/Makefile
index 362c429..c812dcc 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,9 @@ out/main: main.asm impl.asm bootstrap.asm sys.f os/uefi.asm
 	mkdir -p out
 	OS_INCLUDE=os/uefi.asm fasm $< $@
 
+main: main.asm impl.asm bootstrap.asm sys.f os/linux.asm
+	OS_INCLUDE=os/linux.asm fasm $< $@
+
 .PHONY: clean
 clean:
 	rm -rf out OVMF_CODE.fd OVMF_VARS.fd
diff --git a/impl.asm b/impl.asm
index dd7fc9d..67d11b5 100644
--- a/impl.asm
+++ b/impl.asm
@@ -1,6 +1,4 @@
-;; vim: syntax=fasm
-
-section '.text' code readable executable
+os_code_section
 
 macro printlen msg, len {
   push rsi
@@ -186,7 +184,7 @@ parse_number:
   mov rax, 100
   call os_terminate
 
-section '.data' readable writable
+os_data_section
 
 find.search_length dq ?
 find.search_buffer dq ?
diff --git a/main.asm b/main.asm
index 407d3a3..d1ff2b3 100644
--- a/main.asm
+++ b/main.asm
@@ -1,10 +1,16 @@
 ;; vim: syntax=fasm
 
 ;; At compile-time we load the module given by the environment variable
-;; OS_INCLUDE. This module should define the following macros:
+;; OS_INCLUDE. All of the following these procedures should preserve the value
+;; of RSI and RSP. They may use other registers as they like.
 ;;
-;; Each of these functions should preserve the value of RSI and RSP. They may
-;; use other registers as they like.
+;; The module should provide the following:
+;;
+;; os_code_section
+;;   Macro to start the text segment.
+;;
+;; os_data_section
+;;   Macro to start the data segment.
 ;;
 ;; os_initialize
 ;;   Called at initialization.
@@ -78,7 +84,7 @@ macro forth_asm label, name, immediate {
 .start:
 }
 
-section '.text' code readable executable
+os_code_section
 
 include "impl.asm"      ; Misc. subroutines
 include "bootstrap.asm" ; Forth words encoded in Assembly
@@ -609,7 +615,7 @@ forth INPUT_LENGTH, 'INPUT-LENGTH'
   dq LIT, input_buffer_length
   dq EXIT
 
-section '.data' readable writable
+os_data_section
 
 ;; The LATEST variable holds a pointer to the word that was last added to the
 ;; dictionary. This pointer is updated as new words are added, and its value is
@@ -657,6 +663,8 @@ return_stack_top:
 ;; We store some Forth code in sys.f that defined common words that the user
 ;; would expect to have available at startup. To execute these words, we just
 ;; include the file directly in the binary, and then interpret it at startup.
-sysf file 'sys.f'
+sysf:
+file 'sys.f'
+file 'example.f'
 sysf.len = $ - sysf
 
diff --git a/os/linux.asm b/os/linux.asm
new file mode 100644
index 0000000..1279597
--- /dev/null
+++ b/os/linux.asm
@@ -0,0 +1,22 @@
+format ELF64 executable
+
+macro os_code_section {
+  segment readable executable
+}
+
+macro os_data_section {
+  segment readable writable
+}
+
+os_initialize:
+  ret
+
+os_print_string:
+  ret
+
+os_read_char:
+  ret
+
+os_terminate:
+  ret
+
diff --git a/os/uefi.asm b/os/uefi.asm
index 16fc85d..10c7627 100644
--- a/os/uefi.asm
+++ b/os/uefi.asm
@@ -58,6 +58,14 @@ struct EFI_INPUT_KEY
 
 ;; }}}
 
+macro os_code_section {
+  section '.text' code readable executable
+}
+
+macro os_data_section {
+  section '.data' readable writable
+}
+
 section '.text' code executable readable
 
 os_initialize: