itest command

Synopsis

itest[.b | .w | .l | .q | .s] [*]<value1> <op> [*]<value2>

Description

The itest command is used to compare two values. The return value $? is set accordingly.

By default it is assumed that the values are 4 byte integers. By appending a postfix (.b, .w, .l, .q, .s) the size can be specified:

postfix

meaning

.b

1 byte integer

.w

2 byte integer

.l

4 byte integer

.q

8 byte integer (only available if CONFIG_PHYS_64BIT=y)

.s

string

value1, value2

values to compare. Numeric values are hexadecimal. If ‘*’ is prefixed a hexadecimal address is passed, which points to the value to be compared.

op

operator, see table

operator

meaning

-lt

less than

<

less than

-le

less or equal

<=

less or equal

-eq

equal

==

equal

-ne

not equal

!=

not equal

<>

not equal

-ge

greater or equal

>=

greater or equal

-gt

greater than

>

greater than

Examples

The itest command sets the result variable $? to true (0) or false (1):

=> itest 3 < 4; echo $?
0
=> itest 3 == 4; echo $?
1

This value can be used in the if command:

=> if itest 0x3002 < 0x4001; then echo true; else echo false; fi
true

Numbers will be truncated according to the postfix before comparing:

=> if itest.b 0x3002 < 0x4001; then echo true; else echo false; fi
false

Postfix .s causes a string compare. The string ‘0xa1234’ is alphabetically smaller than ‘0xb’.

=> if itest.s 0xa1234 < 0xb; then echo true; else echo false; fi
true

A value prefixed by ‘*’ is a pointer to the value in memory.

=> mm 0x4000
00004000: 00000004 ?
00004004: 00000003 ? =>
=> if itest *0x4000 == 4; then echo true; else echo false; fi
true
=> if itest *0x4004 == 3; then echo true; else echo false; fi
true

Configuration

The command is only available if CONFIG_CMD_ITEST=y.

Return value

The return value $? is 0 (true) if the condition is true and 1 (false) otherwise.