diff options
Diffstat (limited to 'twasm/asm/main.asm')
| -rw-r--r-- | twasm/asm/main.asm | 89 |
1 files changed, 84 insertions, 5 deletions
diff --git a/twasm/asm/main.asm b/twasm/asm/main.asm index 1dfad3b..12f54fd 100644 --- a/twasm/asm/main.asm +++ b/twasm/asm/main.asm @@ -18,6 +18,7 @@ STACK_ADDR equ 0x00060000 ; address to put the 64-bit stack at UNRECOGNISED_TOKEN_ID equ 0xFFFF ; id of an unrecognised token UNRECOGNISED_ID_TYPE equ 0x0F ; type of an unrecognised id UNRECOGNISED_ID_METADATA equ 0xFF ; metadata of an unrecognised id +UNRECOGNISED_ID_OPCODE equ 0x90 ; opcode of an unrecognised id (NOP) TEST_LINE_LENGTH equ 80 ; right border of test suite results @@ -81,24 +82,43 @@ assemble: je .operator jne .continue_operator - .operator + .operator: push rsi mov rsi, .msg_found_operator call print pop rsi - .continue_operator + push rdi + + ; di = tte + call get_tte_typed_metadata + ; al = tte typed metadata + + pop rdi + + and al, 11b ; mask for # operands + + cmp al, 0 ; 0 operands + je .operator_0 + jne .continue_operator0 + + .operator_0: + jmp .continue_operator + + .continue_operator0: + + .continue_operator: cmp ax, 0x02 ; check if it's a register je .register jne .continue_register - .register + .register: push rsi mov rsi, .msg_found_register call print pop rsi - .continue_register + .continue_register: pop rax ; incrementer pop rdi ; total number of tokens @@ -109,6 +129,8 @@ assemble: ret .msg_found_operator db "found operator", 0x0A, 0x00 .msg_found_register db "found register", 0x0A, 0x00 + .next_register dw UNRECOGNISED_TOKEN_ID + .next_next_register dw UNRECOGNISED_TOKEN_ID ; ------------------------------------------------------------------------------ ; get_tte_type @@ -185,6 +207,7 @@ get_tte_typed_metadata: ret .found: mov al, [3 + tokens.by_id + rax * 4] + and rax, 0xFF ret ; ------------------------------------------------------------------------------ @@ -199,7 +222,7 @@ get_tte_typed_metadata: ; si = token table entry `R/M` ; ; returned: -; al = ModR/M byte +; al = ModR/M byte; the rest of rax is zeroed ; ------------------------------------------------------------------------------ get_direct_addressing_ModRM: @@ -245,6 +268,43 @@ get_direct_addressing_ModRM: ret ; ------------------------------------------------------------------------------ +; get_opcode +; +; description: +; given an operator token, returns its opcode +; +; parameters: +; di = token table entry +; +; returned: +; al = opcode; the rest of rax is zeroed +; ------------------------------------------------------------------------------ + +get_opcode: + and rdi, 0xFFFF + xor eax, eax + + .loop: + cmp rax, (opcodes.by_id_end - opcodes.by_id) / 4 ; make sure it's still in range + jg .not_found + + mov cx, [opcodes.by_id + rax * 4] ; next entry in opcodes.by_id + + cmp cx, di + je .found + + inc rax + jmp .loop + .not_found: + xor eax, eax + mov al, UNRECOGNISED_ID_OPCODE + ret + .found: + mov al, [2 + opcodes.by_id + rax * 4] + and rax, 0xFF ; mask + ret + +; ------------------------------------------------------------------------------ ; tokenising ; ------------------------------------------------------------------------------ @@ -961,6 +1021,25 @@ tokens: db 0x00 ; # operands .by_id_end: +opcodes: + .by_id: + dw 0x0053 ; xor + db 0x33 + db 0x00 ; reserved + + dw 0x0054 ; inc + db 0xFF + db 0x00 ; reserved + + dw 0x0056 ; mov + db 0x8B + db 0x00 ; reserved + + dw 0x004F ; hlt + db 0xF4 + db 0x00 ; reserved + .by_id_end: + msg_welcome db "Welcome to Twasm", 0x0A, 0x00 msg_halt db "halted.", 0x0A, 0x00 |