HP 3000 Manuals HP 3000 Manuals
HP C/XL BYTECMP Function: Byte Comparison
/*************************************************************
BYTECMP SPL COMPARE BYTE STRINGS
This emulates the byte string compare expression in SPL,
for example:
IF A < B,(N),0;
NN := TOS; <<count>>
@AA := TOS; <<left address after compare>>
@BB := TOS; <<right address after compare>>
This may be converted to C with:
if (BYTECMP(a,LSS,b,n,0,&nn,&aa,&bb))...
The parameters to BYTECMP are:
left -- The left address to be compared.
cmp -- The comparison to be made, where:
LSS means <
LEQ means <=
EQU means ==
NEQ means !=
GEQ means >=
GTR means >
right -- The right address to be compared.
count -- The maximum number of bytes to compare.
sdec -- The SPL stack decrement. In this context,
the value of this parameter will determine if
the function accesses the last parameter
as follows:
sdec = 3 -- Ignore last three parameters
(in SPL, this is the default
case, deleting 3 stack words).
sdec = 2 -- Expect only one parameter
after this: caddr.
sdec = 1 -- Expect two parameters after
this: caddr and laddr.
sdec = 0 -- Expect three parameters after
this: caddr, laddr, and
raddr.
caddr -- The value of count at the conclusion of the
comparison. If the strings compare for
count bytes, caddr will equal zero.
laddr -- The address of the char within the left
string which failed to match.
raddr -- The address of the char within the right
string which failed to match.
***************************************************************/
enum CMP {LSS, LEQ, EQU, NEQ, GEQ, GTR };
short int BYTECMP(left,cmp,right,count,sdec,caddr,laddr,raddr)
char *left, *right, **laddr, **raddr;
enum CMP cmp;
int count, sdec, *caddr;
{
#define ADJ {if (count>0) {--count;++left;++right;} \
else {++count;--eft;--right;}}
switch (cmp) {
case LSS: /* compare < */
while ((count != 0) && (*left < *right)) ADJ;
break;
case LEQ: /* compare <= */
while ((count != 0) && (*left <= *right)) ADJ;
break;
case EQU: /* compare == */
while ((count != 0) && (*left == *right)) ADJ;
break;
case NEQ: /* compare != */
while ((count != 0) && (*left != *right)) ADJ;
break;
case GEQ: /* compare >= */
while ((count != 0) && (*left >= *right)) ADJ;
break;
case GTR: /* compare > */
while ((count != 0) && (*left > *right)) ADJ;
break;
}
switch (sdec) {
case 0: *raddr = right;
case 1: *laddr = left;
case 2: *caddr = count;
case 3: ; /* nil */
}
return (count == 0);
#undef ADJ
}