mirror of
https://github.com/mikpe/pdp10-tools.git
synced 2026-01-13 15:27:35 +00:00
45 lines
1.3 KiB
C
45 lines
1.3 KiB
C
/*
|
|
* pdp10-extint.c
|
|
*
|
|
* Provide types and procedures for converting 18 and 36-bit integers
|
|
* to and from arrays of 9-bit bytes (nonets). Use these together with
|
|
* pdp10_fread() and pdp10_fwrite() to convert 18 and 36-bit integers
|
|
* between host-level and file-level binary representations.
|
|
*/
|
|
#include "pdp10-extint.h"
|
|
|
|
/*
|
|
* The behaviour of the PDP10's byte pointers implies a big-endian storage model,
|
|
* as does the layout of its 72-bit long integers.
|
|
*/
|
|
|
|
void pdp10_uint18_to_ext(pdp10_uint18_t val, struct pdp10_ext_uint18 *ext)
|
|
{
|
|
ext->nonet[0] = (val >> 9) & 0x1FF;
|
|
ext->nonet[1] = val & 0x1FF;
|
|
}
|
|
|
|
pdp10_uint18_t pdp10_uint18_from_ext(const struct pdp10_ext_uint18 *ext)
|
|
{
|
|
return
|
|
((pdp10_uint18_t)(ext->nonet[0] & 0x1FF) << 9)
|
|
| (ext->nonet[1] & 0x1FF);
|
|
}
|
|
|
|
void pdp10_uint36_to_ext(pdp10_uint36_t val, struct pdp10_ext_uint36 *ext)
|
|
{
|
|
ext->nonet[0] = (val >> 27) & 0x1FF;
|
|
ext->nonet[1] = (val >> 18) & 0x1FF;
|
|
ext->nonet[2] = (val >> 9) & 0x1FF;
|
|
ext->nonet[3] = val & 0x1FF;
|
|
}
|
|
|
|
pdp10_uint36_t pdp10_uint36_from_ext(const struct pdp10_ext_uint36 *ext)
|
|
{
|
|
return
|
|
((pdp10_uint36_t)(ext->nonet[0] & 0x1FF) << 27)
|
|
| ((pdp10_uint36_t)(ext->nonet[1] & 0x1FF) << 18)
|
|
| ((pdp10_uint36_t)(ext->nonet[2] & 0x1FF) << 9)
|
|
| (ext->nonet[3] & 0x1FF);
|
|
}
|