The assembly code has this format:
label: mnemonic operand_list ;comment
Each part is not mandatory. Here is an example of a (useless and buggy) loop:
init:
mov.b 0, R4 ; initialize the R4 register with 0 (decimal)
loop:
add.b 1, R4 ; add 1 to R4
nop ; no operation (and no operand)
jmp loop
Labels
The labels are symbols corresponding to a memory address. They must begin in the first column.
Mnemonics:
the mnemonics can correspond to - instructions (mov, bitc, jmp, ...) - Assembler directives (.cdecls, .data, .sect, ...) - macros
The mnemonics are suffixed with ".b" or ".w", depending if we want to work with a byte (8 bits) or a word (16 or 32 bits depending the microcontroller)
The usual mnemonics instructions are:
Bit / Register instructions:
| Operation | operand | Description | C | V | N | Z | Emulated |
|---|---|---|---|---|---|---|---|
| BIC(.B) | src,dst | .not.src .and. dst → dst clear bits in destination |
|||||
| BIS(.B) | src,dst | src .or. dst → dst set bits in destination |
|||||
| CLR(.B) | dst | mov #0, dst Clear destination |
yes | ||||
| MOV(.B) | src,dst | src → dst copy (not move) source to destination |
|||||
| CLRC | bic #1, SR Clear carry bit |
0 | yes | ||||
| CLRN | bic #4, SR Clear negative bit |
0 | yes | ||||
| CLRZ | bic #2, SR Clear zero bit |
0 | yes | ||||
| SETC | bis #1, SR Set carry bit |
1 | yes | ||||
| SETN | bis #4, SR Set negative bit |
1 | yes | ||||
| SETZ | bis #2, SR Set zero bit |
1 | yes |
Logic instructions:
| Operation | operand | Description | C | V | N | Z | Emulated |
|---|---|---|---|---|---|---|---|
| XOR(.B) | src,dst | src .xor. dst → dst xor source with destination |
x | x | x | x | |
| AND(.B) | src,dst | src .and. dst → dst | 0 | x | x | x | |
| BIS(.B) | src,dst | src .or. dst → dst | |||||
| INV(.B) | dst | #OFFFFh .xor. dst Invert destination |
x | x | x | x | yes |
Arithmetic instructions:
| Operation | operand | Description | C | V | N | Z | Emulated |
|---|---|---|---|---|---|---|---|
| ADC(.B) | dst | dst + C → dst Add carry to destination |
x | x | x | x | |
| ADD(.B) | src,dst | src + dst → dst Add source to destination |
x | x | x | x | |
| ADDC(.B) | src,dst | src + dst + C → dst Add source and carry to destination |
x | x | x | x | |
| DADC(.B) | dst | dst + C → dst (decimal) Decimal add carry to destination |
x | x | x | x | yes |
| DADD(.B) | src,dst | src + dst + C → dst (decimal) Decimal addition |
x | x | x | x | |
| DEC(.B) | dst | dst - 1 → dst Decrement destination |
x | x | x | x | yes |
| DECD(.B) | dst | dst - 2 → dst Decrement destination twice |
x | x | x | x | yes |
| INC(.B) | dst | dst +1 → dst Increment destination |
x | x | x | x | yes |
| INCD(.B) | dst | dst+2→dst Increment destination twice |
x | x | x | x | yes |
| SUB(.B) | src,dst | dst + .not.src + 1 → dst Substract source from destination |
x | x | x | x | |
| SUBC(.B) | src,dst | dst + .not.src + C → dst Substract source and carry from destination |
x | x | x | x | |
| SBC(.B) | dst | Subtract carry from destination | x | x | x | x | yes |
Tests/comparisons operations:
| Operation | operand | Description | C | V | N | Z | Emulated |
|---|---|---|---|---|---|---|---|
| CMP(.B) | src,dst | dst - src Compare src with dst |
x | x | x | x | |
| BIT(.B) | src,dst | src .and. dst Test bits in destination |
0 | x | x | x | |
| TST(.B) | dst | cmp #0, dst Test destination |
x | x | x | x | yes |
Program flow
| Operation | operand | Description | C | V | N | Z | Emulated |
|---|---|---|---|---|---|---|---|
| CALL | dst | PC+2 → stack, dst → PC Subroutine call to destination |
|||||
| RETI | TOS → SR, SP + 2 → SP TOS → PC, SP + 2 → SZP Return from interrupt |
||||||
| RET | TOS → PC, SP + 2 → SP Return from subroutine |
yes | |||||
| BR | dst mov dst, PC Branch to destination |
yes | |||||
| DINT | bic #8, SR Disable general interrupts |
yes | |||||
| EINT | bis #8, SR Enable general interrupts |
yes | |||||
| NOP | mov #0, R3 No operation |
yes | |||||
| JC/JHS | Label Jump to Label if Carry-bit is set | ||||||
| JEQ/JZ | Label Jump to Label if Zero-bit is set | ||||||
| JGE | Label Jump to Label if (N .XOR. V) = 0 | ||||||
| JL | Label Jump to Label if (N .XOR. V) = 1 | ||||||
| JMP | Label Jump to Label unconditionally | ||||||
| JN | Label Jump to Label if Negative-bit is set | ||||||
| JNC/JLO | Label Jump to Label if Carry-bit is reset | ||||||
| JNE/JNZ | Label Jump to Label if Zero-bit is reset |
(TOS) = Top Of Stack
Others
| Operation | operand | Description | C | V | N | Z | Emulated |
|---|---|---|---|---|---|---|---|
| POP(.B) | dst | &SP→temp, SP+2 → SP, temp→dst Item from stack |
yes | ||||
| PUSH(.B) | src | SP - 2 → SP, src → @SP Push source on stack |
|||||
| RLA(.B) | dst | add dst, dst Rotate left arithmetically (dest x 2) |
x | x | x | x | yes |
| RLC(.B) | dst | addc dst, dst Rotate left through carry |
x | x | x | x | yes |
| RRA(.B) | dst | MSB → MSB ....LSB → C Roll destination right |
0 | x | x | x | |
| RRC(.B) | dst | C → MSB .........LSB → C Roll destination right through carry |
x | x | x | x | |
| SWPB | dst | swap bytes swap bytes in destination |
|||||
| SXT | dst | Bit7 → Bit8 ........ Bit15 Sign extend destination |
0 | x | x | x |
The usual assembler directives are:
| directive | description |
|---|---|
| .cdecls [options,] "filename" | Import a C header file in the assembly code |
| .def symbol1 [, ... , symboln] | Identifies one or more symbols that are defined in current module |
| .text | Assembles into the .text (executable code) section |
| .retain | Override ELF conditional linking and retain current section |
| .retainrefs | Retain any sections that have references to current section. |
| .end | Ends program |
Source: TI assembly mnemonics local cache
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