Maxim Integrated DS4830 Optical Microcontroller - Manual (Page 198)

DS4830 User’s Guide
198
{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