Implement UEFI functionality in Forth

[rrq/jonasforth.git] / main.asm

diff --git a/main.asm b/main.asm
index 5985b997af8095926394802fd7e6c59b636a5510..5f63d849b92f156a1a66e0e3b7fa1819c35280ac 100644 (file)
--- a/main.asm
+++ b/main.asm
@@ -1,10 +1,5 @@
-;; vim: syntax=fasm
-
-;; At compile-time we load the module given by the environment variable
-;; OS_INCLUDE. This module should define the following macros:
-;;
-;; Each of these functions should preserve the value of RSI and RSP. They may
-;; use other registers as they like.
+;; The UEFI module defines the following functions. Each of these functions
+;; preserve the value of RSI and RSP. They may use other registers as they like.
 ;;
 ;; os_initialize
 ;;   Called at initialization.
@@ -15,61 +10,11 @@
 ;;
 ;; os_read_char
 ;;   Wait for the user to type a key, and then put the corresponding ASCII byte
-;;   into the buffer pointed to by RCX.
+;;   into RAX.
 ;;
 ;; os_terminate
-;;   Shut down the system.
-include '%OS_INCLUDE%'
-
-;; Print a string of a given length.
-;;
-;; Input:
-;; - RCX = Pointer to buffer
-;; - RDX = Buffer length
-;;
-;; Clobbers: RAX, RCX, R11, RDI, RSI
-macro sys_print_string {
-  push r8
-  push r9
-  push r10
-
-  call os_print_string
-
-  pop r10
-  pop r9
-  pop r8
-}
-
-;; Read a character from the user into the given buffer.
-;;
-;; Input:
-;; - RSI = Character buffer
-;;
-;; Output:
-;; - BYTE [RSI] = Character
-;;
-;; Clobbers: RAX, RCX, R11, RDI, RSI, RDX
-macro sys_read_char {
-  push rbx
-  push r8
-  push r9
-  push r10
-  push r15
-
-  mov rcx, rsi
-  call os_read_char
-
-  pop r15
-  pop r10
-  pop r9
-  pop r8
-  pop rbx
-}
-
-macro sys_terminate code {
-  mov rax, code
-  call os_terminate
-}
+;;   Shut down the system, returning the error code given in RAX.
+include 'os/uefi.asm'
 
 ;; 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
@@ -240,7 +185,7 @@ forth_asm EMIT, 'EMIT'
 
   lea rcx, [rsp]
   mov rdx, 1
-  sys_print_string
+  call os_print_string
 
   add rsp, 8
   popr rax
@@ -265,12 +210,7 @@ forth_asm KEY, 'KEY'
   jne .from_buffer
 
   ;; Reading user input
-  push rsi
-  mov rsi, .buffer
-  sys_read_char
-  pop rsi
-
-  movzx rax, byte [.buffer]
+  call os_read_char
   ret
 
 .from_buffer:
@@ -341,7 +281,7 @@ forth_asm TELL, 'TELL'
 
   pop rdx ; Length
   pop rcx ; Buffer
-  sys_print_string
+  call os_print_string
 
   popr rsi
   popr rax
@@ -349,7 +289,8 @@ forth_asm TELL, 'TELL'
 
 ;; Exit the program cleanly.
 forth_asm TERMINATE, 'TERMINATE'
-  sys_terminate 0
+  mov rax, 0
+  call os_terminate
 
 ;; Duplicate a pair of elements.
 forth_asm PAIRDUP, '2DUP'
@@ -438,7 +379,7 @@ forth_asm DOTU, '.U'
   ;; Print the buffer
   mov rcx, .buffer
   mov rdx, [.printed_length]
-  sys_print_string
+  call os_print_string
 
   ;; Restore RSI and continue execution
   pop rsi
@@ -511,10 +452,7 @@ forth_asm READ_STRING, 'S"'
   mov [.length], 0
 
 .read_char:
-  mov rsi, .char_buffer
-  sys_read_char
-
-  mov al, [.char_buffer]
+  call os_read_char
   cmp al, '"'
   je .done
 
@@ -639,6 +577,69 @@ forth MAIN, 'MAIN'
   dq BRANCH, -8 * 2
   dq TERMINATE
 
+;; EFI:
+
+forth EFI_SYSTEM_TABLE_CONSTANT, 'SystemTable'
+  dq LIT, system_table, GET
+  dq EXIT
+
+forth_asm EFICALL2, 'EFICALL2'
+  pop rax ; function pointer
+  pop rdx ; 2nd argument
+  pop rcx ; 1st argument
+
+  sub rsp, 32
+  call rax
+  add rsp, 32
+
+  next
+
+forth_asm EFICALL3, 'EFICALL3'
+  pop rax ; function pointer
+  pop r8  ; 3rd argument
+  pop rdx ; 2nd argument
+  pop rcx ; 1st argument
+
+  sub rsp, 32
+  call rax
+  add rsp, 32
+
+  push rax
+
+  next
+
+forth_asm EFICALL10, 'EFICALL10'
+  pop rax ; function pointer
+
+  mov rcx, [rsp + 8 * 9]
+  mov rdx, [rsp + 8 * 8]
+  mov r8, [rsp + 8 * 7]
+  mov r9, [rsp + 8 * 6]
+
+  ;; Reverse order of stack arguments
+  mov r10, [rsp + 8 * 5]
+  mov r11, [rsp + 8 * 0]
+  mov [rsp + 8 * 5], r11
+  mov [rsp + 8 * 0], r10
+
+  mov r10, [rsp + 8 * 4]
+  mov r11, [rsp + 8 * 1]
+  mov [rsp + 8 * 4], r11
+  mov [rsp + 8 * 1], r10
+
+  mov r10, [rsp + 8 * 3]
+  mov r11, [rsp + 8 * 2]
+  mov [rsp + 8 * 3], r11
+  mov [rsp + 8 * 2], r10
+
+  sub rsp, 32
+  call rax
+  add rsp, 32 + 8 * 10
+
+  push rax
+
+  next
+
 ;; Built-in variables:
 
 forth STATE, 'STATE'
@@ -714,6 +715,8 @@ 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 'uefi.f'
 sysf.len = $ - sysf