Assembler:Commands:CALL

command call size operand

Calls the given operand (address or function), jumps to the given operand then returns.

Note: A RET must be hit for a CALL to work properly, best to use JMPs if unsure.

Saves procedure linking information on the stack and branches to the procedure (called procedure) specified with the destination (target) operand. The target operand specifies the address of the first instruction in the called procedure. This operand can be an immediate value, a general purpose register, or a memory location.

This instruction can be used to execute four different types of calls:

Near call

A call to a procedure within the current code segment (the segment currently pointed to by the CS register), sometimes referred to as an intrasegment call.

Far call

A call to a procedure located in a different segment than the current code segment, sometimes referred to as an intersegment call.

Inter-privilege-level far call

A far call to a procedure in a segment at a different privilege level than that of the currently executing program or procedure.

Task switch

A call to a procedure located in a different task.

c9x.me/x86/html/file_module_x86_id_26.html

Command Parameters

Parameter	Description
size OPTIONAL	The preferred size of the assembled address
operand	The address or symbol to call

Examples

call +1A   // Call from end of command to +1A (hex).

call 00123ABC   // Call the address.

call 0000123456ABCDEF   // Call the address.

call eax   // Call the value of eax.

call rax   // Call the value of rax.

call someSymbol   // Call the user defined symbol.

call someLabel   // Call the label.

call short someLabel   // Call the label with short byte code.

call long someLabel   // Call the label with full address.

call @b   // Call back the closest label

call @f   // Call forward the closest label

Running this script in 32 bit mode:

globalAlloc(memTest, 0x200)
label(testLbl)
memTest:
                          add [eax],al // db 00 00
@@:
                          add [eax],al
                          ret
call short @b
call short @f
                          add [eax],al
@@:
                          add [eax],al
                          ret
                          add [eax],al
call short -8
call short +2
                          add [eax],al
testLbl:
                          add [eax],al
                          ret
call 02EA0002
                          add [eax],al
call eax
                          add [eax],al
call memTest
                          add [eax],al
call testLbl
                          add [eax],al
call short testLbl
                          add [eax],al
call long testLbl
                          add [eax],al
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

Running this script in 64 bit mode:

globalAlloc(memTest, 0x200)
label(testLbl)
memTest:
                          add [rax],al // db 00 00
@@:
                          add [rax],al
                          ret
call short @b
call short @f
                          add [rax],al
@@:
                          add [rax],al
                          ret
                          add [rax],al
call short -8
call short +2
                          add [rax],al
testLbl:
                          add [rax],al
                          ret
call 01160002
                          add [rax],al
call rax
                          add [rax],al
call memTest
                          add [rax],al
call testLbl
                          add [rax],al
call short testLbl
                          add [rax],al
call long testLbl
                          add [rax],al
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

See also

• Assembler
• Auto Assembler
• Assembler Commands

External links

• wikipedia.org/wiki/X86_instruction_listings
• wikibooks.org/wiki/X86_Assembly/Other_Instructions
• c9x.me/x86/
• ref.x86asm.net
• https://www.felixcloutier.com/x86