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as supports the following additional command-line options
for the V850 processor family:
-wsigned_overflow
-
Causes warnings to be produced when signed immediate values overflow the
space available for then within their opcodes. By default this option
is disabled as it is possible to receive spurious warnings due to using
exact bit patterns as immediate constants.
-wunsigned_overflow
-
Causes warnings to be produced when unsigned immediate values overflow
the space available for then within their opcodes. By default this
option is disabled as it is possible to receive spurious warnings due to
using exact bit patterns as immediate constants.
-mv850
-
Specifies that the assembled code should be marked as being targeted at
the V850 processor. This allows the linker to detect attempts to link
such code with code assembled for other processors.
`#' is the line comment character.
as supports the following names for registers:
general register 0
-
r0, zero
general register 1
-
r1
general register 2
-
r2, hp
general register 3
-
r3, sp
general register 4
-
r4, gp
general register 5
-
r5, tp
general register 6
-
r6
general register 7
-
r7
general register 8
-
r8
general register 9
-
r9
general register 10
-
r10
general register 11
-
r11
general register 12
-
r12
general register 13
-
r13
general register 14
-
r14
general register 15
-
r15
general register 16
-
r16
general register 17
-
r17
general register 18
-
r18
general register 19
-
r19
general register 20
-
r20
general register 21
-
r21
general register 22
-
r22
general register 23
-
r23
general register 24
-
r24
general register 25
-
r25
general register 26
-
r26
general register 27
-
r27
general register 28
-
r28
general register 29
-
r29
general register 30
-
r30, ep
general register 31
-
r31, lp
system register 0
-
eipc
system register 1
-
eipsw
system register 2
-
fepc
system register 3
-
fepsw
system register 4
-
ecr
system register 5
-
psw
The V850 family uses IEEE floating-point numbers.
.offset <expression>
-
Moves the offset into the current section to the specified amount.
.section "name", <type>
-
This is an extension to the standard .section directive. It sets the
current section to be <type> and creates an alias for this section
called "name".
.v850
-
Specifies that the assembled code should be marked as being targeted at
the V850 processor. This allows the linker to detect attempts to link
such code with code assembled for other processors.
as implements all the standard V850 opcodes.
as also implements the following pseudo ops:
hi0()
-
Computes the higher 16 bits of the given expression and stores it into
the immediate operand field of the given instruction. For example:
`mulhi hi0(here - there), r5, r6'
computes the difference between the address of labels 'here' and
'there', takes the upper 16 bits of this difference, shifts it down 16
bits and then mutliplies it by the lower 16 bits in register 5, putting
the result into register 6.
lo()
-
Computes the lower 16 bits of the given expression and stores it into
the immediate operand field of the given instruction. For example:
`addi lo(here - there), r5, r6'
computes the difference between the address of labels 'here' and
'there', takes the lower 16 bits of this difference and adds it to
register 5, putting the result into register 6.
hi()
-
Computes the higher 16 bits of the given expression and then adds the
value of the most significant bit of the lower 16 bits of the expression
and stores the result into the immediate operand field of the given
instruction. For example the following code can be used to compute the
address of the label 'here' and store it into register 6:
`movhi hi(here), r0, r6'
`movea lo(here), r6, r6'
The reason for this special behaviour is that movea performs a sign
extention on its immediate operand. So for example if the address of
'here' was 0xFFFFFFFF then without the special behaviour of the hi()
pseudo-op the movhi instruction would put 0xFFFF0000 into r6, then the
movea instruction would takes its immediate operand, 0xFFFF, sign extend
it to 32 bits, 0xFFFFFFFF, and then add it into r6 giving 0xFFFEFFFF
which is wrong (the fifth nibble is E). With the hi() pseudo op adding
in the top bit of the lo() pseudo op, the movhi instruction actually
stores 0 into r6 (0xFFFF + 1 = 0x0000), so that the movea instruction
stores 0xFFFFFFFF into r6 - the right value.
sdaoff()
-
Computes the offset of the named variable from the start of the Small
Data Area (whoes address is held in register 4, the GP register) and
stores the result as a 16 bit signed value in the immediate operand
field of the given instruction. For example:
`ld.w sdaoff(_a_variable)[gp],r6'
loads the contents of the location pointed to by the label '_a_variable'
into register 6, provided that the label is located somewhere within +/-
32K of the address held in the GP register. [Note the linker assumes
that the GP register contains a fixed address set to the address of the
label called '__gp'. This can either be set up automatically by the
linker, or specifically set by using the `--defsym __gp=<value>'
command line option].
tdaoff()
-
Computes the offset of the named variable from the start of the Tiny
Data Area (whoes address is held in register 30, the EP register) and
stores the result as a
7 or 8 bit unsigned value in the immediate
operand field of the given instruction. For example:
`sld.w tdaoff(_a_variable)[ep],r6'
loads the contents of the location pointed to by the label '_a_variable'
into register 6, provided that the label is located somewhere within +256
bytes of the address held in the EP register. [Note the linker assumes
that the EP register contains a fixed address set to the address of the
label called '__ep'. This can either be set up automatically by the
linker, or specifically set by using the `--defsym __ep=<value>'
command line option].
zdaoff()
-
Computes the offset of the named variable from address 0 and stores the
result as a 16 bit signed value in the immediate operand field of the
given instruction. For example:
`movea zdaoff(_a_variable),zero,r6'
puts the address of the label '_a_variable' into register 6, assuming
that the label is somewhere within the first 32K of memory. (Strictly
speaking it also possible to access the last 32K of memory as well, as
the offsets are signed).
For information on the V850 instruction set, see V850
Family 32-/16-Bit single-Chip Microcontroller Architecture Manual from NEC.
Ltd.
@raisesections
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