Microchip Technology SW006023-2N Data Sheet

 2012 Microchip Technology Inc.

DS51686E-page 89

When the CP0 register definitions header file is included from an Assembly file, the 
CP0 registers are defined as:

#define _CP0_register_name $register_number, select_number

For example, the IntCtl register is defined as:

#define _CP0_INTCTL $12, 1

When the CP0 register definitions header file is included from a C file, the CP0 registers 
and selects are defined as:

#define _CP0_register_name register_number

#define _CP0_register_name_SELECT select_number

For example, the IntCtl register is defined as:

#define _CP0_INTCTL 12

#define _CP0_INTCTL_SELECT 1

When the CP0 register definitions header file is included from either an Assembly or a 
C/C++ file, three #defines exist for each of the CP0 register fields.

_CP0_register_name_field_name_POSITION

 – the starting bit location

_CP0_register_name_field_name_MASK

 – the bits that are part of this field are 

set

_CP0_register_name_field_name_LENGTH

 – the number of bits that this field 

occupies

For example, the vector spacing field of the IntCtl register has the following defines:

#define _CP0_INTCTL_VS_POSITION 0x00000005

#define _CP0_INTCTL_VS_MASK     0x000003E0

#define _CP0_INTCTL_VS_LENGTH   0x00000005

When the CP0 register definitions header file is included from a C file, CP0 access 
macros are defined. Each CP0 register may have up to six different access macros 
defined:

_CP0_GET_register_name ()

Returns the value for register,  

register_name

.

_CP0_SET_register_name (val)

Sets the register, 

register_name

, to val, and 

returns void. Only defined for registers that contain a 
writable field.

_CP0_XCH_register_name (val)

Sets the register, 

register_name

, to val, and 

returns the previous register value. Only defined for 
registers that contain a writable field.

_CP0_BIS_register_name (set)

Sets the register, 

register_name

, to (reg |= set), 

and returns the previous register value. Only defined 
for registers that contain writable bit fields.

_CP0_BIC_register_name (clr)

Sets the register, 

register_name

, to (reg &= ~clr), 

and returns the previous register value. Only defined 
for registers that contain writable bit fields.

_CP0_BCS_register_name (clr, 

set)

Sets the register, 

register_name

, to 

(reg = (reg & ~clr) | set), and returns the previous 
register value. Only defined for registers that contain 
writable bit fields.