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/* reloc.h - assemble for HP-PA */
/* Defines machine specific relocation entries */
#ifndef HPPA_RELOC_INCLUDED
#define HPPA_RELOC_INCLUDED
/*
* Relocation types used in the hppa implementation. Relocation entries for
* things other than instructions use the same generic relocation as discribed
* in <mach-o/reloc.h> and their r_type is HPPA_RELOC_VANILLA. The rest of the
* relocation types are for instructions. Since they are for instructions the
* r_address field indicates the 32 bit instruction that the relocation is to
* be preformed on. The field r_pcrel is set only for the HPPA_RELOC_BR17.
* And r_length is set to long for all non-RELOC_VANILLA r_types.
*/
enum reloc_type_hppa
{
HPPA_RELOC_VANILLA, /* generic relocation as discribed in <mach-o/reloc.h>*/
HPPA_RELOC_PAIR, /* the second relocation entry of a pair */
HPPA_RELOC_HI21, /* a PAIR follows with the low part */
HPPA_RELOC_LO14, /* a PAIR follows with the high part */
HPPA_RELOC_BR17, /* 17 bit branch displacement (to a word address)
a PAIR follows with the high part */
HPPA_RELOC_BL17, /* a bl instruction (overlow causes an error) */
HPPA_RELOC_JBSR, /* a bl instruction that is targeted at a long branch
stub, a PAIR follows with the high part */
HPPA_RELOC_SECTDIFF, /* a PAIR follows with subtract symbol value */
HPPA_RELOC_HI21_SECTDIFF, /* a PAIR follows with subtract symbol value */
HPPA_RELOC_LO14_SECTDIFF /* a PAIR follows with subtract symbol value */
};
/*
* For the HI and LO relocation types the two parts of the relocated expression
* (symbol + offset) are calculated as follows:
*
* rounded = round(offset, 0x2000);
* left21 = (symbol + rounded) & 0xfffff800;
* right14 = ((symbol + rounded) & 0x000007ff) + (offset - rounded);
*
* This allows the left part to be shared between references with different
* offsets as long as the rounded offsets are the same.
*
* The HPPA_RELOC_BR17 r_type also uses the above calculation and the right14
* bits, sign extened to fill the displacement, and converted to a word
* displacement by droping the low bits (after checking they are zero).
*/
/*
* For relocation types that use pairs the part of the relocated expression that
* is not stored in the instruction is stored in the r_address feild of the
* PAIR's entry.
*
* All low parts are stored as sign extened byte addressed values in the PAIR's
* r_address field as 32 bit values. This allows the HI21 not to have to know
* which type of low it is used with.
*
* The high parts are left justified 21 bit values zero filled to 32 bits and
* stored in the PAIR's r_address field.
*/
/*
* The instructions that use the non-RELOC_VANILLA r_types are and the r_types
* they use are as follows:
* instructions r_type
*
* LDIL,ADDIL HPPA_RELOC_HI21
* LDx, STx, LDO HPPA_RELOC_LO14
* BE, BLE HPPA_RELOC_BR17
* BL HPPA_RELOC_BL17
*
* For the HPPA_RELOC_JBSR the BL instruction must be targeted at a long branch
* stub that can be reached with 17 bits of signed word displacement. Also the
* stub must be in the same block as the BL instruction so that scattered
* loading done by the link editor will not move them apart. For example in
* assembly code:
* jbsr foo,%r2,L1 ; creates a bl inst with a HPPA_RELOC_JBSR
* ; relocation entry for the symbol foo and the
* ; instruction is targeted to L1
* ...
* L1: ldil L'foo,%r1 ; a HPPA_RELOC_HI21 entry for symbol foo
* ble,n R'foo(%sr4,%r1) ; a HPPA_RELOC_BR17 entry for symbol foo
*/
#endif /* HPPA_RELOC_INCLUDED */
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