CC78K4 datasheet(160/523 Pages) NEC

160 / 523 page

CHAPTER 10 LIBRARY FUNCTIONS

User’s Manual U15556EJ1V0UM

160

10.1.2 Return values

The return value of a function is stored in units of 16 bits starting from its LSB in the direction from the register BC

to the register RPZ. When returning a structure, the first address of the structure is stored in the register BC. When

returning a pointer, the first address of the structure is stored in the register BC.

The following shows the list of storing the return value. The method of storing return values is the same as that of

normal functions.

Table 10-2. List of Storing Return Value

Return Value Type

Small Model

Medium Model

Large Model

1 bit

1-byte, 2-byte integers

4-byte integers

BC (lower), RP2 (higher)

Floating-point number

(float type)

BC (lower), RP2 (higher)

Floating-point number

(double type)

BC (lower), RP2 (higher)

Structure

Copies the structure to return

to the area specific to the

function and stores the

address in BC

Copies the structure to return

to the area specific to the

function and stores the

address in BC

Copies the structure to return

to the area specific to the

function and stores the

address in TDE

Pointer

BC (function pointer)

WHL (function pointer)

TDE

10.1.3 Saving registers to be used by individual libraries

Each library that uses RP3, RG4 (VVP) and RG5 (UUP) saves the registers it uses to a stack.

Each library that uses a saddr area saves the saddr area it uses to a stack. A stack area is used as a work area

for each library.

(1) When -ZR option is not specified

The procedure of passing arguments and return values is shown below. An example of the small model is shown

below.

Called function “long func (int a, long b, char *c) ;”

CC78K4 датащи(PDF) 160 Page - NEC

CC78K4 датащи(HTML) 160 Page - NEC

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL