a)HLL b) 68K x:=x+1 ADDQ.W #1,X IF A=7 THEN CMPI.W #7,A B:=3; BNE NEXT C:=4; MOVEQ #3,B END IF MOVEQ #4,C x:=X+2; NEXT: ADDQ.W #2,X b) At. Programmation Structurée En Assembleur by J.-P. Malengé, S. Albertsen, P. Collard and L. Andréani Masson, Paris, pages. ABCD. Operation: Source(base 10) + Destination (base 10) –>; Destination. Compatibility: Family. Assembler Syntax: ABCD Dy, Dx ABCD -(Ay), -(Ax).
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One thing to note is that the PowerPC is not binary compatible with the 68K processor.
Ifs, Loops and the DBRA instruction
Assemboeur, Apple has written an emulator in PowerPC assembly language which aswembleur PowerPC microprocessors to interpret machine language code written for 68K microprocessors, albeit with a substantial performance decrease versus native PowerPC machine language. Note that there is no postdecrement or preincrement addressing mode. Typically, there are only a few places you’ll want to refer to, for example the starting points of functions, loop starts and loop ends, and certain data storage locations.
Policies and guidelines Contact us. After the instruction, both registers contain the same information. You can have as many labels as you want. This bit is always cleared on processor models lower than Not supported by all devices. This label can then be used as an operand anywhere a number can. In other languages Add links. It can also be used as a pointer in PC relative addressing modes. This is known as forward referencingand is handled differently depending on the assembler.
Wikipedia has more about this subject:. They are usually used in Jcc or Bcc instructions. Like absolute near, you can include the parentheses at your discretion. The 68K instruction set is very orthogonal.
See External Links below. Views Read Edit View history. You can help by splitting this big page into smaller ones. The 68K includes special addressing modes that make it easy to manipulate a data stack structure using any address register.
Retrieved from ” https: The Program Counter PC points to the current instruction. This bit is always clear on processor models lower than The only instructions that are allowed to use this addressing mode are: There is one active stack pointer: This document contains information on how to program the Motorola 68K-series microprocessors in assembly language.
In supervisor mode, the entire bit register is accessible.
Assembly – Wikibooks, open books for an open world
Normally the processor is in user mode. When the instruction is executed, both registers will contain the same information. This may change the size of the label, in which case a third pass will be needed, and so on.
SP, also called a7. SR is only available in supervisor mode. When a word is transferred to an address register, bit 15 the sign bit will be copied through the whole upper word bit There are eight data registers: Which you choose is largely a matter of personal preference, but most people find xxx.
Take care with this!!! Note that PC is the address of the extension word that x is stored in right after the instruction’s word. Usually, it just uses a known safe value like the current PCflags the location, and makes a second pass to substitute the real value. Copies the contents of D1 to D0.
From Wikibooks, open books for an open world. SR is the entire status register, including the system byte. The assembler you use may have different behavior. Operate on the location pointed to by xxx. Only the lower byte is accessible in user mode, and of this, only the first five bits are useful.
On theonly the lower 24 bits output to any pins, giving a maximum addressing range of 16MiB. The assembler handles labels as aliases for numbers. Some assemblers won’t take certain syntaxes. Not all assemblers will take awsembleur listed syntaxes.
If it wasn’t so, a negative number would become positive. Wherever you see “cc” in an instruction, you should replace it with the appropriate conditional test code.