#include <SCSI.h>

typedef struct SCSIInstr { Size Offset Description

unsigned short scOpcode;}2 0 operation code

unsigned long scParam1; 4 2 first parameter

unsigned long scParam2; 4 6 second parameter

A transfer instructions block tells the SCSI Manager what to do with

the data bytes transferred during the data phase. A transfer instruction block

contains a pseudo-program consisting of a variable number of instructions;

it's similar to a subroutine except that the instructions are provided and

interpreted by the SCSI Manager itself. The instructions are of a fixed size

Eight instructions are available; their operation codes are specified with the

scInc SCINC instruction

scNoInc SCNOINC instruction

scAdd SCADD instruction

scMove SCMOVE instruction

scLoop SCLOOP instruction

scNOp SCNOP instruction

scStop SCSTOP instruction

A description of the instructions is given below:

scOpcode = scInc scParam1 = buffer scParam2 = count

The SCINC instruction moves count bytes to or from buffer, incrementing

scOpcode = scNoInc scParam1 = buffer scParam2 = count

The SCNOINC instruction moves count data bytes to or from buffer, leaving

scOpcode = scAdd scParam1 = addr scParam2 = value

The SCADD instruction adds the given value to the address in addr. (The

addition is performed as an MC68000 operation.)

scOpcode = scMove scParam1 = addr1 scParam2 = addr2

The SCMOVE instruction moves the value pointed to by addr1 to the location

pointed to by addr2. (The move is an MC68000 long operation)

scOpcode = scLoop param1 = relAddr param2 = count

The SCLOOP instruction decrements count by 1. If the result is greater than

0, pseudo-program execution resumes at the current address+relAddr. If the

result is 0, pseudo-program execution resumes at the next instruction.

RelAddr should be a signed multiple of the instruction size (10 bytes). For

example, to loop to the immediately preceding instruction, the relAddr field

would contain -10. To loop forward by three instructions, it would contain 30.

scOpcode = scNOp scParam1 = NIL scParam2 = NIL

scOpcode = scStop scParam1 = NIL scParam2 = NIL

The SCSTOP instruction terminates the pseudo-program execution, returning

scOpcode = scComp scParam1 = addr scParam2 = count

The SCCOMP instruciton is used only with a read command. Beginning at addr,

it compares incoming data bytes with memory, incoming data bytes with

memory, incrementing addr by count when done. If the bytes do not compare

equally, an error is returned to the read command.

This example give a transfer instruction block for a transfer of six 512-byte