MSP430 Instructions
4-90
16-Bit MSP430X CPU
JN
Jump if Negative
Syntax
JN
label
Operation
If N = 1:
PC + (2
×
Offset)
→
PC
If N = 0:
execute following instruction
Description
The negative bit N in the status register is tested. If it is set, the signed 10-bit
word offset contained in the instruction is multiplied by two, sign extended, and
added to the 20-bit program counter PC. This means a jump in the range -511
to +512 words relative to the PC in the full memory range. If N is reset, the
instruction after the jump is executed.
Status Bits
Status bits are not affected
Mode Bits
OSCOFF, CPUOFF, and GIE are not affected
Example
The byte COUNT is tested. If it is negative, program execution continues at
Label0. Data in lower 64 K, program in full memory range.
TST.B
&COUNT
; Is byte COUNT negative?
JN
Label0
; Yes, proceed at Label0
...
; COUNT
≥
0
Example
R6 is subtracted from R5. If the result is negative, program continues at
Label2. Program in full memory range.
SUB
R6,R5
; R5 − R6 -> R5
JN
Label2
; R5 is negative: R6 > R5 (N = 1)
...
; R5
≥
0. Continue here.
Example
R7 (20-bit counter) is decremented. If its content is below zero, the program
continues at Label4. Program in full memory range.
SUBA
#1,R7
; Decrement R7
JN
Label4
; R7 < 0: Go to Label4
...
; R7
≥
0. Continue here.
Содержание MSP430x4xx Family
Страница 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Страница 2: ......
Страница 6: ...vi ...
Страница 114: ...3 76 RISC 16 Bit CPU ...
Страница 304: ...5 20 FLL Clock Module ...
Страница 340: ...7 8 Supply Voltage Supervisor ...
Страница 348: ...8 8 16 Bit Hardware Multiplier ...
Страница 372: ...9 24 32 Bit Hardware Multiplier ...
Страница 400: ...10 28 DMA Controller ...
Страница 428: ...13 10 Basic Timer1 ...
Страница 466: ...15 24 Timer_A ...
Страница 522: ...17 30 USART Peripheral Interface UART Mode ...
Страница 544: ...18 22 USART Peripheral Interface SPI Mode ...
Страница 672: ...23 12 Comparator_A ...
Страница 692: ...24 20 LCD Controller ...
Страница 746: ...26 28 ADC12 ...