X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=main.asm;h=537d0e8e6fe3e3728bc06704d8925001e27f739e;hb=4170f15b09ccd8bcafc00bb960a6e56670252256;hp=691e9f363d352fc95f351beabb2a30f05b14615a;hpb=1878070fedd3dec11082913df12a57f97b69cb12;p=rrq%2Fjonasforth.git

diff --git a/main.asm b/main.asm
index 691e9f3..537d0e8 100644
--- a/main.asm
+++ b/main.asm
@@ -1,6 +1,6 @@
 ;; vim: syntax=fasm
 
-format ELF64 executable
+include "uefi.asm"
 
 ;; "Syscalls" {{{
 
@@ -22,10 +22,15 @@ format ELF64 executable
 ;;
 ;; Clobbers: RAX, RCX, R11, RDI, RSI
 macro sys_print_string {
-  mov rax, 1
-  mov rdi, 1
-  mov rsi, rcx
-  syscall
+  push r8
+  push r9
+  push r10
+
+  call uefi_print_string
+
+  pop r10
+  pop r9
+  pop r8
 }
 
 ;; Read a character from the user into the given buffer.
@@ -38,16 +43,25 @@ macro sys_print_string {
 ;;
 ;; Clobbers: RAX, RCX, R11, RDI, RSI, RDX
 macro sys_read_char {
-  mov rax, 0
-  mov rdi, 0
-  mov rdx, 1
-  syscall
+  push rbx
+  push r8
+  push r9
+  push r10
+  push r15
+
+  mov rcx, rsi
+  call uefi_read_char
+
+  pop r15
+  pop r10
+  pop r9
+  pop r8
+  pop rbx
 }
 
 macro sys_terminate code {
-  mov rax, $3C
-  mov rdi, code
-  syscall
+  mov rax, code
+  call uefi_terminate
 }
 
 ;; }}}
@@ -109,9 +123,7 @@ macro forth_asm label, name, immediate {
 .start:
 }
 
-segment readable executable
-
-entry main
+section '.text' code readable executable
 
 include "impl.asm"      ; Misc. subroutines
 include "bootstrap.asm" ; Forth words encoded in Assembly
@@ -120,6 +132,8 @@ main:
   cld                        ; Clear direction flag so LODSQ does the right thing.
   mov rbp, return_stack_top  ; Initialize return stack
 
+  call uefi_initialize
+
   mov rax, MAIN
   jmp qword [rax]
 
@@ -217,38 +231,77 @@ forth_asm EMIT, 'EMIT'
   popr rsi
   next
 
-;; Read a word and push it onto the stack as a pointer and a size. The pointer
-;; is valid until the next call to READ_WORD.
-forth_asm READ_WORD, 'READ-WORD'
+;; Read a single character from the current input stream. Usually, this will wait
+;; for the user to press a key, and then return the corresponding character. When
+;; reading from a special buffer, it will instead return the next characater from
+;; that buffer.
+;;
+;; The ASCII character code is placed on the stack.
+forth_asm KEY, 'KEY'
+  call .impl
+  push rax
+  next
+
+;; Result in RAX
+.impl:
   ;; Are we reading from user input or from the input buffer?
   cmp [input_buffer], 0
   jne .from_buffer
 
   ;; Reading user input
-  mov [.rsi], rsi
-
-  call read_word
-  push rdi                      ; Buffer
-  push rdx                      ; Length
+  push rsi
+  mov rsi, .buffer
+  sys_read_char
+  pop rsi
 
-  mov rsi, [.rsi]
-  next
+  movzx rax, byte [.buffer]
+  ret
 
 .from_buffer:
   ;; Reading from buffer
-  mov [.rsi], rsi
+  mov rax, [input_buffer]
+  movzx rax, byte [rax]
+
+  inc [input_buffer]
+  dec [input_buffer_length]
+  ret
+
+;; Read a word and push it onto the stack as a pointer and a size. The pointer
+;; is valid until the next call to READ_WORD.
+forth_asm READ_WORD, 'READ-WORD'
+  push rsi
+.skip_whitespace:
+  ;; Read characters until one of them is not whitespace.
+  call KEY.impl
+  ;; We consider newlines and spaces to be whitespace.
+  cmp al, ' '
+  je .skip_whitespace
+  cmp al, $A
+  je .skip_whitespace
+
+  ;; We got a character that wasn't whitespace. Now read the actual word.
+  mov [.length], 0
 
-  mov rsi, [input_buffer]
-  mov rcx, [input_buffer_length]
+.read_alpha:
+  movzx rbx, [.length]
+  mov rsi, .buffer
+  add rsi, rbx
+  mov [rsi], al
+  inc [.length]
 
-  call pop_word
+  call KEY.impl
 
-  mov [input_buffer], rsi        ; Updated buffer
-  mov [input_buffer_length], rcx ; Length of updated buffer
-  push rdi                       ; Word buffer
-  push rdx                       ; Length of word buffer
+  cmp al, ' '
+  je .end
+  cmp al, $A
+  jne .read_alpha
+
+.end:
+  pop rsi
+  push .buffer
+  movzx rax, [.length]
+  push rax
 
-  mov rsi, [.rsi]
   next
 
 ;; Takes a string on the stack and replaces it with the decimal number that the
@@ -597,7 +650,7 @@ forth INPUT_LENGTH, 'INPUT-LENGTH'
   dq LIT, input_buffer_length
   dq EXIT
 
-segment readable writable
+section '.data' readable writable
 
 ;; 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
@@ -629,6 +682,11 @@ DOTU.rbuffer rq 16
 DOTU.length dq ?
 DOTU.printed_length dq ?
 
+KEY.buffer dq ?
+
+READ_WORD.buffer rb $FF
+READ_WORD.length db ?
+
 ;; Reserve space for compiled words, accessed through HERE.
 here dq here_top
 here_top rq $4000
@@ -637,8 +695,6 @@ here_top rq $4000
 rq $2000
 return_stack_top:
 
-segment readable
-
 ;; 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.