Short tour of PAL
Contents
Short tour of PAL in release 0.6.x
In release 0.6.x, only the PROSE Assembly Language (PAL) is available, and then only a subset of those instructions. So be aware, it's very low-level programming at this time. To learn more about the PROSE Programming Language, visit http://prose.sourceforge.net.
It is suggested you begin with the following articles before attempting this tour.
This article gives a brief tour of the following features in the PROSE Assembly Language.
Registers and indices
There are 93 unique instruction codes (opcodes) in PAL, 15 registers, 8 special register keywords and 5 data entry macros. Run prism -l and you'll see a list of them all:
$ prism -l
------------------------------------------------------------
INSTRUCTIONS
0x80 noop
0x81 stack/push
0x82 stack/pull
0x83 stack/peek
0x84 stack/lock
0x85 stack/unlock
0x86 stack/flush
0x89 obj/def
0x8a obj/clone
0x8b obj/edit
0x8c obj/commit
0x8d obj/del
0x8e obj/addr
0x8f obj/pa
0x90 obj/child
0x91 obj/dump
0x92 class/add
0x93 class/del
0x94 class/load
0x95 class/load()
0x96 class/test
0x97 attr/add
0x98 attr/del
0x99 attr/mod
0x9a attr/mvadd
0x9b attr/mvdel
0x9c attr/mvmod
0x9d attr/load
0x9e attr/load()
0x9f attr/test
0xa0 attr/mvtest
0xa1 attr/copy
0xa2 attr/copy()
0xa3 attr/direct
0xa6 op/incr
0xa7 op/decr
0xa8 op/add
0xa9 op/sub
0xaa op/mult
0xab op/div
0xac op/mod
0xad op/not
0xae op/and
0xaf op/or
0xb0 op/xor
0xb1 op/shl
0xb2 op/shr
0xb3 op/mask
0xb4 op/swap
0xbc error/def
0xbd error/now
0xbe error/jmp
0xbf error/clr
0xc0 func/def
0xc1 func/call
0xc2 func/bcall
0xc3 func/rtn
0xc4 local/jmp()
0xc5 local/jsr()
0xc6 local/jmp
0xc7 local/jsr
0xc8 local/rtn
0xc9 reg/move
0xca reg/load
0xcb reg/jmpeq
0xcc reg/jmpneq
0xcd reg/jsreq
0xce reg/jsrneq
0xcf reg/dump
0xd0 reg/load()
0xd1 reg/clr
0xd2 reg/index
0xd3 reg/cmp
0xd4 reg/save()
0xd5 reg/copy
0xd6 reg/copy()
0xd7 reg/conv
0xd8 reg/lcmp
0xd9 reg/rcmp
0xda reg/scan
0xe8 opa/add
0xe9 opa/sub
0xea opa/mult
0xeb opa/div
0xec opa/mod
0xed opa/not
0xee opa/and
0xef opa/or
0xf0 opa/xor
0xf1 opa/shl
0xf2 opa/shr
0xfb debug/source
0xfc debug/level
------------------------------------------------------------
INDICES (with Accumulator)
0x60 to 0x63 A, LABEL
0x64 to 0x67 A, DLABEL
0x68 to 0x6b A, OBJREF
0x6c to 0x6f A, TEXT
0x70 to 0x73 A, RAW
0x7c ------- A, PTRPOS
0x7d ------- A, PTRNEG
------------------------------------------------------------
INDICES (without Accumulator)
0x40 to 0x43 LABEL
0x44 to 0x47 DLABEL
0x48 to 0x4b OBJREF
0x4c to 0x4f TEXT
0x50 to 0x53 RAW
0x5c ------- PTRPOS
0x5d ------- PTRNEG
------------------------------------------------------------
REGISTERS (with Accumulator)
0x20 A, P0
0x21 A, P1
0x22 A, P2
0x23 A, P3
0x24 A, P4
0x25 A, P5
0x26 A, P6
0x27 A, P7
0x28 A, P8
0x29 A, P9
0x2a A, P10
0x2b A, P11
0x2c A, P12
0x2d A, P13
0x37 A, A
0x38 A, SFLG
0x39 A, SCMP
0x3a A, LOCK
0x3b A, PCTX
0x3c A, PEEK
0x3d A, PULL
0x3e A, PUSH
0x3f A, NULL
------------------------------------------------------------
REGISTERS (without Accumulator)
0x00 P0
0x01 P1
0x02 P2
0x03 P3
0x04 P4
0x05 P5
0x06 P6
0x07 P7
0x08 P8
0x09 P9
0x0a P10
0x0b P11
0x0c P12
0x0d P13
0x17 A
0x18 SFLG
0x19 SCMP
0x1a LOCK
0x1b PCTX
0x1c PEEK
0x1d PULL
0x1e PUSH
0x1f NULL
------------------------------------------------------------
MACROS
0x20 EQUB
0x40 EQUW
0x60 EQUD
0x80 EQUS
0xa0 EQUP
Registers are pointers to units of data. They can point to text strings, nodes (objects in the nexus), program code, and a variety of other data types. The type of data is always associated with the register, so that bytecode instructions can validate, to a certain degree, that the arguments they have been given are correct.
Besides registers, other valid arguments that may be passed to PAL instructions are called indices. An index parameter is so called because when it is compiled into bytecode, it is saved to a table, and the argument itself converted to a numeric index. There are 7 types of index, although only 5 of these can be used explicitly within a PAL source file. Indices allow for data such as arbitrary text, code references and object references to be input.
The following code example demonstrates the use of registers and indices. It loads text and code pointers into a number of registers, and then dumps the contents to the screen.
% This program will only have a ._init section for now
._init
% Load registers P0 and P1
reg/load P0, [A violin concerto], P1, [Brahms]
reg/load P10, &[._init], P11, [Brahms]
% Report contents of registers
reg/dump P0, P1, P10, P11
obj/dump P0, P1, P10, P11
Compile and run the code:
$ prism test
$ prose test
register: P0
type: PSUNIT_TYPE_PALTEXT
0x2b82b788504b (len 0x000011)
register: P1
type: PSUNIT_TYPE_PALTEXT
0x2b82b788505e (len 0x000006)
register: P10
type: PSUNIT_TYPE_PALCODE
0x0000
register: P11
type: PSUNIT_TYPE_PALTEXT
0x2b82b788505e (len 0x000006)
0x2b82b788504b (len 0x000011)
A violin concerto
0x2b82b788505e (len 0x000006)
Brahms
0x2b82b788505e (len 0x000006)
Brahms
prose: ERROR: no main() function found, nothing to do
The error 'no main() function found' means that the PROSE engine could only call _init sections and there was no main function from which to begin full program execution. For the purposes of this exercise the error can be ignored. For simplicity we have omitted defining a main function (as functions are described later on in this tour).
If you run prism -v on the binary, you'll see that the text 'A violin concerto' and 'Brahms' were given the index numbers 0 and 1 respectively. Note that even though the text 'Brahms' appeared twice in the source file, it only has one entry in the text table.
$ prism -v test
------------------------------------------------------------
PROSE HEADER
File: test.pro
Size: 112 bytes
Compiled by: prism
Compiler version code: 0.6.0
Compile date: Wed Sep 30 11:51:25 2009
------------------------------------------------------------
INSTRUCTION CODE
000000 : ca 00 4c 00 01 4c 01 ca 0a 5d 09 0b 4c 01 cf 00
000010 : 01 0a 0b 91 00 01 0a 0b
Size: 24 bytes
------------------------------------------------------------
CODE LABELS
idx 000000 len 000005 [_init]
Size: 7 bytes
------------------------------------------------------------
CODE ADDRESSES
idx 000000 ref 000000
Size: 1 bytes
------------------------------------------------------------
TEXT DATA
idx 000000 len 000011 [A violin concerto]
idx 000001 len 000006 [Brahms]
Size: 27 bytes
------------------------------------------------------------
DATA LABELS
Size: 0 bytes
------------------------------------------------------------
DATA XREF TABLE
Size: 0 bytes
------------------------------------------------------------
DATA SEGMENTS
Size: 0 bytes
------------------------------------------------------------
END OF FILE
