TSC80251 TEMIC [TEMIC Semiconductors], TSC80251 Datasheet - Page 37

• Manufacturer Part Number: TSC80251
• Manufacturer: TEMIC [TEMIC Semiconductors]

TSC80251
4.6.2. Conditional Jumps
The C251 Architecture supports bit–conditional jumps, compare–conditional jumps, and jumps based on the value of
the accumulator. A bit–conditional jump is based on the state of a bit. In a compare–conditional jump, the jump is based
on a comparison of two operands. All conditional jumps are relative, and the target address (rel) must be in the current
256–byte block of code. The instruction set includes three kinds of bit–conditional jumps :
Compare–conditional jumps test a condition resulting from a compare (CMP) instruction that is assumed to precede
the jump instruction. The jump instruction examines the PSW and PSW1 registers and interprets their flags as though
they were set or cleared by a compare (CMP) instruction. Actually, the state of each flag is determined by the last
instruction that could have affected that flag.
The condition flags are used to test one of the following six relations between the operands :
For each relation there are two instructions, one for signed operands and one for unsigned operands (See Table 4.11. ).
4.12
Relative, 8-bit relative address (rel)
Direct, 11-bit target address (addr11)
Direct, 16-bit target address (addr16)
Direct, 24-bit target address (addr24)
Indirect (@WRj)
Indirect (@A +DPTR)
Note:
Unsigned
Signed
JB (Jump on Bit): Jump if the bit is set.
JNB (Jump on Not Bit): Jump if the bit is clear.
JBC (Jump on Bit then Clear it): Jump if the bit is set; then clear it.
equal (=), not equal ( )
greater than (>), less than (<)
greater than or equal ( ), less than or equal ( )
Operand
Operand
These modes are not used by instructions in the C51 Architecture.
Type
Description
Table 4.10. Addressing Modes for Control Instructions
JE
JE
Table 4.11. Compare-conditional Jump Instructions
JNE
JNE
Address Bits
Provided
11
16
24
16
16
8
JSG
JG
–128 to +127 from first byte of next instruction
Current 2 Kbytes
Current 64 Kbytes
00:0000h-FF:FFFFh
Current 64 Kbytes
64-Kbyte region specified by DPXL (reset value = 01h)
Relation
JSL
JL
Address Range
JSGE
JGE
Rev. C – May 7, 1999
JSLE
JLE