diff options
Diffstat (limited to 'assembler/assemble.s')
| -rw-r--r-- | assembler/assemble.s | 25 |
1 files changed, 11 insertions, 14 deletions
diff --git a/assembler/assemble.s b/assembler/assemble.s index ef3893d..61d4f40 100644 --- a/assembler/assemble.s +++ b/assembler/assemble.s @@ -6,31 +6,30 @@ .global assemble // TODO: -// - implement opcode parser -// - test each instruction (do this later -- much easier) -// - test 4-bit reg instructions -// - test BEQ overlaps +// - test each instruction // - decide on additional push or pops +// - add data literal "instructions" +// - redo_line is problematic assemble: - // LDR R3, [SP, 20] + PUSH {LR} MOVS R6, 0 - LDR R7, =0x00C8E893 - // LDR R7, =0xE0E3A588 MOVS R0, ' MOV R8, R0 + BL opcode + MOV R0, R8 + BL uart_send + MOVS R7, R4 main_loop: LSRS R0, R7, 8 // just peek BNE skip // if more stuff then skip MOVS R0, '\r MOV R8, R0 //set end char to carriage return skip: - // MOVS R0, 0xFF // lsb mask - // ANDS R0, R7 // store in R0 UXTB R0, R7 // store lsb in R0 LSRS R1, R0, 4 // upper nibble CMP R1, 0xC // if 0xxxxxxx or 10xxxxxx - BLO opcode + BLO handle_opcode CMP R1, 0xE // if 110xyyyy BLO handle_imm handle_reg: // if 111xyyyy @@ -43,7 +42,7 @@ handle_reg: // if 111xyyyy LSLS R4, R0 // shift the result by the shift amount ORRS R6, R4 // OR the register code into the word under construction B done_stuff -opcode: +handle_opcode: MOVS R2, 9 // shift amount for 7-bit opcode MOVS R1, (1<<7) // bit 7 mask TST R0, R1 // check bit 7 @@ -78,9 +77,7 @@ here: done: MOVS R0, '\n // send newline BL uart_send - MOVS R0, R6 - BL send_hex - B assemble + POP {PC} .type get_char, %function .global get_char |