Maxim Integrated MAXQ610 - Manual (Page 172)

14-5
MAXQ610 User’s Guide
{L/S}CALL src {Long/Short} Call to Subroutine
Description: Performs a call to the subroutine destination specified by src . The CALL instruction uses an 8-bit
immediate src to perform a relative short call (IP +127/-128 words) . The CALL instruction uses a
16-bit immediate src to perform an absolute long CALL 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 long CALL .
Using the optional ‘L’ prefix (i .e ., LCALL) will result in an absolute long call and use of the PFX[0]
register . Using the optional ‘S’ prefix (i .e ., SCALL) will attempt to generate a relative short call, 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 CALL 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: @++SP ← IP + 1 PUSH
IP ← src Absolute CALL
IP ← IP + src Relative CALL
Encoding: 15 0
f011 1101 ssss ssss
Example(s): CALL label1 ; relative call to label1 (must be within
; IP +127/-128 address range)
CALL label1 ; absolute call to label1 = 0120h
; MOVE PFX[0], #01h
; CALL #20h .
CALL DP[0] ; DP[0] holds 16-bit address of subroutine
CALL M0[0] ; assume M0[0] is an 8-bit register
; absolute call to addr16
; high(addr16)=00h (PFX[0])
; low (addr16)=M0[0]
MOVE PFX[0], #22h ;
CALL M0[0] ; assume M0[0] is an 8-bit register
; high(addr16)=22h (PFX[0])
; low (addr16)=M0[0]
LCALL label1 ; label=0120h and is relative to this instruction
; absolute call is forced by use of ‘L’ prefix
; MOVE PFX[0], #01h
; CALL #20h
SCALL label1 ; relative offset for label1 calculated and used
; if label1 is not relative, assembler will generate an
; error
SCALL #10h ; relative offset of #10h is used directly by the CALL