diff options
| -rw-r--r-- | assembler/assemble.s | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/assembler/assemble.s b/assembler/assemble.s new file mode 100644 index 0000000..96940ea --- /dev/null +++ b/assembler/assemble.s @@ -0,0 +1,77 @@ +1yyyxxxx Imm yyy = shift amount xxxx = bit-width +00000001 Brackets +0011yyyy Reg yyyy = shift amount +0100yyyy Reg + +MOVS 0x 00 00 88 38 +ADDS 0x 00 00 88 38 +SUBS 0x 00 00 88 38 +CMP 0x 00 00 33 30 +ANDS 0x 00 00 33 30 +ORRS 0x 00 00 33 30 +TST 0x 00 00 33 30 +LSLS 0x 00 E5 33 30 +LSRS 0x 00 E5 33 30 +RORS 0x 00 00 33 30 +LDR 0x E5 33 01 30 +LDRB 0x 36 33 01 30 +STR 0x E5 33 01 30 +STRB 0x 36 33 01 30 +B<c> 0x 00 00 00 88 +B 0x 00 00 00 8B +BX 0x 00 00 00 43 + +// R2 holds the whole word +// R0 holds just the byte +// R1 holds either 3 or 4 +more: + MOVS R0, 0xFF + ANDS R0, R2 + MOVS R1, 0x80 + TST R0, R1 + BNE handle_imm // if IMM + MOVS R1, 0xF0 + ANDS R1, R0 + BEQ handle_brackets // if BRACKETS +handle_reg: + LSRS R1, 4 + MOVS R3, 0x0F + ANDS R0, R3 + // R1 = 3 or 4 + // R0 = shift amount + BL register + B done_stuff + +handle_imm: + BL octal + B done_stuff + +handle_brackets: + // expect bracket + // echo bracket + LSRS R2, 0x8 + BEQ next_instr + Back + ... + +done_stuff: + LSRS R2, 0x4 + BEQ done + MOVS R0, 0 + ORRS R0, R9 + BL uart_send // echo the comma (or bracket) +expect: + BL get_char + MOVS R1, ' // space char + CMP R0, R1 + BNE expect // keep trying if not space + BL uart_send // echo the space + B more +done: + TST R8, R8 // R8 == whether we are in bracket or not + BEQ no_brackets + MOVS R0, '] + BL uart_send +no_bracket: + // echo carriage return + newline + B next_instr |