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LOAD_ADDR equ 0x00010000 ; address this program is loaded at
TOKEN_TABLE_ADDR equ 0x00060000 ; address the token table is loaded at
TOKEN_TABLE_SIZE equ 0x1000 ; max length of table
TEST_ARENA_ADDR equ 0x00060000 ; address to run tests at
TEST_ARENA_SIZE equ 0x1000 ; maximum size tests can use
OUTPUT_ADDR equ 0x00070000 ; address of outputed binary
OUTPUT_SIZE equ 0x1000 ; max length of outputed binary
[bits 64]
[org LOAD_ADDR]
start:
mov rsi, msg_welcome
call print
call run_tests
jmp halt
;
; tokenising
;
; copy_token
;
; description:
; copies a token from one spot in memory to another
; and returns metadata about that token
;
; parameters:
; rdi -> start of asm command to be read
; rsi -> start of buffer to be written
;
; returned:
copy_token:
mov rax, rdi
.loop:
cmp al, " "
je .continue
jne .break
.continue:
call copy_byte
.break:
inc rax
ret
; copy_byte
;
; description:
; copies a byte from one spot in memory to another
;
; parameters:
; rdi -> word to be read
; rsi -> word to be written
;
; returned:
; al = byte that was read
copy_byte:
mov al, [rdi]
mov [rsi], al
ret
;
; utilities
;
; print
;
; description:
; prints a null-terminated string
;
; parameters:
; rsi -> start of null-terminated string
; dx = port to output to
print:
.loop:
mov al, [rsi]
test al, al
jz .done
out dx, al
inc rsi
jmp .loop
.done:
ret
; halt
;
; description:
; halts the program, silly :)
halt:
mov rsi, msg_halt
call print
hlt
jmp halt
;
; tests
;
; run_tests
;
; description:
; runs all tests
;
; parameters:
; dx = port to output to
run_tests:
mov rsi, .msg
call print
call test_copy_byte
ret
.msg db "running test suite...", 0x0D, 0x0A, 0x00
; test_copy_byte
;
; description:
; makes sure copy_byte function works by testing the following
; - that it copies one byte to a specified memory address
; - that it returns the copied byte in al
;
; parameters:
; dx = port to output to
test_copy_byte:
mov rsi, .msg
call print
mov rdi, test_byte ; byte to be copied
mov rsi, TEST_ARENA_ADDR ; location of test
call copy_byte
mov cx, [rsi]
cmp ax, cx ; compare returned byte to copied byte
jne .fail
je .pass
.pass:
mov rsi, msg_pass
call print
ret
.fail:
mov rsi, msg_fail
call print
ret
.msg db "test_copy_byte...", 0x00
;
; data
;
msg_welcome db "Welcome to Twasm", 0x0D, 0x0A, 0x00
msg_halt db "halted.", 0x0D, 0x0A, 0x00
msg_pass db "passed.", 0x0D, 0x0A, 0x00
msg_fail db "failed.", 0x0D, 0x0A, 0x00
test_byte db "T"
test_token db "Test Token" ; two tokens, one followed by a space and one by nothing
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