14.1 Register Variables

Table 14-1. Register Conventions
Variable	Working Register
`char, signed char, unsigned char`	W0-W13, and W14, if not used as a Frame Pointer
`short, signed short, unsigned short`	W0-W13, and W14, if not used as a Frame Pointer
`int, signed int, unsigned int`	W0-W13, and W14, if not used as a Frame Pointer
`void * (or any pointer)`	W0-W13, and W14, if not used as a Frame Pointer
`long, signed long, unsigned long`	A pair of contiguous registers, the first of which is a register from the set {W0, W2, W4, W6, W8, W10, W12}
`long long, signed long long, unsigned long long`	A quadruplet of contiguous registers, the first of which is a register from the set {W0, W4, W8}. Successively higher-numbered registers contain successively more significant bits.
`float`	A pair of contiguous registers, the first of which is a register from the set {W0, W2, W4, W6, W8, W10, W12}
`double`^1.	A pair of contiguous registers, the first of which is a register from the set {W0, W2, W4, W6, W8, W10, W12}
`long double`	A quadruplet of contiguous registers, the first of which is a register from the set {W0, W4, W8}
`structure`	1 contiguous register per 2 bytes in the structure
`_Fract` `_Sat _Fract`	W0-W13, and W14, if not used as a Frame Pointer
`long _Fract` `_Sat long _Fract`	A pair of contiguous registers, the first of which is a register from the set {W0, W2, W4, W6, W8, W10, W12}
`_Accum` `_Sat _Accu`m	Three contiguous registers where the first register starts in the set {W0, W4, W8, W12}; W12 is included only if W14 is not used as a frame pointer.
Note 1: `double` is equivalent to `long double` if `-fno-short-double` is used.