single: itest (command)
itest[.b | .w | .l | .q | .s] [*]<value1> <op> [*]<value2>
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
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 <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
The command is only available if CONFIG_CMD_ITEST=y.
The return value $? is 0 (true) if the condition is true and 1 (false) otherwise.