diff options
Diffstat (limited to 'twasm/asm/main.asm')
| -rw-r--r-- | twasm/asm/main.asm | 77 |
1 files changed, 67 insertions, 10 deletions
diff --git a/twasm/asm/main.asm b/twasm/asm/main.asm index 69708bc..9c052e1 100644 --- a/twasm/asm/main.asm +++ b/twasm/asm/main.asm @@ -90,6 +90,7 @@ assemble: mov [.tokens_total], edi ; edi = total number of tokens in table .loop: + call .flush_write_buffer call .get_next_tte ; di = tte call get_tte_type @@ -129,7 +130,7 @@ assemble: call get_opcode ; al = opcode ; dl = 0x00 - call .output_byte + call .write_byte jmp .loop_next_token @@ -143,7 +144,7 @@ assemble: ; al = opcode ; dl = op flag push rdx - call .output_byte + call .write_byte pop rdx ; dl = op flag call .next_token @@ -165,7 +166,7 @@ assemble: cmp al, 0x02 ; type: register je .operator_1_register - jmp .loop_next_token + jmp .unexpected_token .operator_1_memory: mov rsi, .msg_operator_1_memory @@ -183,7 +184,7 @@ assemble: mov edx, 11b ; dl = mod bits call get_ModRM ; al = Mod R/M byte - call .output_byte + call .write_byte jmp .loop_next_token @@ -212,7 +213,7 @@ assemble: cmp al, 0x02 ; type: register je .operator_2_register - jmp .loop_next_token + jmp .unexpected_token .operator_2_memory: mov rsi, .msg_operator_2_memory @@ -226,7 +227,7 @@ assemble: call get_opcode ; al = opcode ; dl = op flag - call .output_byte + call .write_byte call .next_token jge .break @@ -264,7 +265,7 @@ assemble: mov dl, 00b ; dl = mod bits call get_ModRM ; al = Mod R/M byte - call .output_byte + call .write_byte jmp .loop_next_token @@ -279,7 +280,7 @@ assemble: ; al = opcode ; dl = op flag ; TODO do something if the op flag is present - call .output_byte + call .write_byte pop rdi ; di = dst tte mov si, di ; si = dst tte @@ -324,7 +325,7 @@ assemble: mov edx, 00b ; dl = mod bits call get_ModRM ; al = Mod R/M byte - call .output_byte + call .write_byte jmp .loop_next_token @@ -338,7 +339,7 @@ assemble: mov edx, 11b ; dl = mod bits call get_ModRM ; al = Mod R/M byte - call .output_byte + call .write_byte jmp .loop_next_token @@ -348,6 +349,7 @@ assemble: jmp .loop .break: + call .flush_write_buffer ret .unexpected_token: @@ -391,6 +393,59 @@ assemble: .next_output_byte dd OUTPUT_ADDR ; next empty byte in output ; TODO get rid of this sketchy bit of state + ; al = byte to push + .push_byte: + push rcx + mov ecx, [.buffer_pointer] + push rcx + push rax + mov ecx, .buffer_end + mov [.buffer_pointer], ecx + .push_byte_loop: + dec ecx + cmp ecx, .buffer + jl .push_byte_break + mov al, [ecx] + mov [ecx + 1], al + jmp .push_byte_loop + .push_byte_break: + pop rax ; al = byte to push + mov [.buffer], al + pop rcx ; ecx = old buffer pointer + inc ecx + mov [.buffer_pointer], ecx + pop rcx + ret + + ; al = byte to write + .write_byte: + mov edx, [.buffer_pointer] + mov [edx], al + inc edx + mov [.buffer_pointer], edx + ret + + .flush_write_buffer: + push rcx + push rax + mov ecx, [.buffer_pointer] + .flush_write_buffer_loop: + dec ecx + cmp ecx, .buffer + jl .flush_write_buffer_break + mov al, [ecx] + call .output_byte + mov byte [ecx], 0x00 + jmp .flush_write_buffer_loop + .flush_write_buffer_break + mov dword [.buffer_pointer], .buffer + pop rax + pop rcx + ret + .buffer dq 0, 0 ; octo word of space for max of 8 bytes per write + .buffer_end: + .buffer_pointer dd .buffer ; points to current byte in buffer + .msg_unexpected_token db "unexpected token, aborting", 0x0A, 0x00 .msg_unsupported_memory_access db "unsupported memory access, aborting", 0x0A, 0x00 .msg_operator_0 db "operator_0", 0x0A, 0x00 @@ -1991,6 +2046,8 @@ program: db "; one line comment", 0x0A db "mov rdx, [rax]", 0x0A db "mov [rax], rdx", 0x0A + db "mov [rcx], rbx", 0x0A + db "mov rcx, [rbx]", 0x0A db "hlt", 0x0A .size dq $ - program |