diff options
Diffstat (limited to 'assembler/opcode.s')
| -rw-r--r-- | assembler/opcode.s | 43 |
1 files changed, 19 insertions, 24 deletions
diff --git a/assembler/opcode.s b/assembler/opcode.s index 18292ad..588d938 100644 --- a/assembler/opcode.s +++ b/assembler/opcode.s @@ -27,30 +27,25 @@ // R4: start of choices, final result (parse instruction) // R5: choice pointer -opcode: - PUSH {LR} - ADR R4, start // start at the start -get_match: - BL get_char - MOV R5, R4 // reset choice pointer - B first_time // don't increment pointer on first time -next_choice: - ADDS R5, 8 // increment choice pointer -first_time: - LDRB R1, [R5] // load char - TST R1, R1 // test if char is zero - BEQ get_match // if run out of options, get a new char - CMP R0, R1 // check if input matches char - BNE next_choice // if not match try next option - BL uart_send // echo char send if match - LDR R4, [R5, 4] // load parse instruction or offset - LDRB R1, [R5, 1] // load parse instruction vs offset byte - TST R1, R1 // check if zero - BNE get_match // non-zero means it's an address -get_end_char: - BL get_char - BNE get_end_char - POP {PC} // zero means it's a parse instruction +opcode: PUSH {LR} + ADR R4, start // start at the start +10: BLX R10 + MOV R5, R4 // reset choice pointer + B 30f // don't increment pointer on first time +20: ADDS R5, 8 // increment choice pointer +30: LDRB R1, [R5] // load char + TST R1, R1 // test if char is zero + BEQ 10b // if run out of options, get a new char + CMP R0, R1 // check if input matches char + BNE 20b // if not match try next option + BLX R9 // echo char send if match + LDR R4, [R5, 4] // load parse instruction or offset + LDRB R1, [R5, 1] // load parse instruction vs offset byte + TST R1, R1 // check if zero + BNE 10b // non-zero means it's an address +40: BLX R10 + BNE 40b + POP {PC} // zero means it's a parse instruction .align 4 |