User guide

DS4830A User’s Guide
209
{L/S} JUMP src Unconditional {Long/Short} Jump
Description: Performs an unconditional jump as determined by the src specifier. The JUMP instruction
uses an 8-bit immediate src to perform a relative jump (IP +127/-128 words). The JUMP
instruction uses a 16-bit immediate src to perform an absolute JUMP to the specified 16-bit
address. The PFX[0] register is used to supply the high byte of a 16-bit immediate address
for the absolute JUMP. Using the optional ‘L’ prefix (i.e. LJUMP) will result in an absolute
long jump and use of the PFX[0] register. Using the optional ‘S’ prefix (i.e. SJUMP) will
attempt to generate a relative short jump, but will be flagged by the assembler if the
destination is out or range. Specifying an internal register src (no matter whether 8-bit or 16-
bit) always produces an absolute JUMP to a 16-bit address, thus the ‘L’ and ‘S’ prefixes
should not be used. The PFX[n] register value is used to supply the high address byte when
an 8-bit register src is specified.
Status Flags: None
Operation: IP  src Absolute JUMP
IP  IP + src Relative JUMP
Encoding: 15 0
f000
1100
ssss
ssss
Example(s): JUMP label1 ; relative jump to label1 (must be within range
; IP +127/-128 words)
JUMP label1 ; absolute jump to label1= 0400h
; MOVE PFX[0], #04h
; JUMP #00h
JUMP DP[0] ; absolute jump to addr16 DP[0]
JUMP M0[0] ; assume M0[0] is an 8-bit register
; absolute jump to addr16
; high(addr16)=00h (PFX[0])
; low (addr16)=M0[0]
LJUMP label1 ; label=0120h and is relative to this instruction
; absolute jump is forced by use of ‘L’ prefix
; MOVE PFX[0], #01h
; JUMP #20h
SJUMP label1 ; relative offset for label1 calculated and used
; if label1 is not relative, assembler will generate an error
SJUMP #10h ; relative offset of #10h is used directly by the JUMP