mirror of https://github.com/cc65/cc65.git
220 lines
6.7 KiB
C
220 lines
6.7 KiB
C
/*
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!!DESCRIPTION!! C-Manual Chapter 2.6: Hardware Characteristics
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!!ORIGIN!! LCC 4.1 Testsuite
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!!LICENCE!! own, freely distributeable for non-profit. read CPYRIGHT.LCC
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*/
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#include "common.h"
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#ifndef CQ26_INCLUDED
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struct defs {
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int cbits; /* No. of bits per char */
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int ibits; /* int */
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int sbits; /* short */
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int lbits; /* long */
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int ubits; /* unsigned */
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int fbits; /* float */
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int dbits; /* double */
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#ifndef NO_FLOATS
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float fprec; /* Smallest number that can be */
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float dprec; /* significantly added to 1. */
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#endif
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int flgs; /* Print return codes, by section */
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int flgm; /* Announce machine dependencies */
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int flgd; /* give explicit diagnostics */
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int flgl; /* Report local return codes. */
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int rrc; /* recent return code */
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int crc; /* Cumulative return code */
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char rfs[8]; /* Return from section */
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};
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int lbits; /* long */
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int ubits; /* unsigned */
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int fbits; /* float */
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int dbits; /* double */
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#ifndef NO_FLOATS
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float fprec; /* Smallest number that can be */
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float dprec; /* significantly added to 1. */
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#endif
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int flgs; /* Print return codes, by section */
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int flgm; /* Announce machine dependencies */
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int flgd; /* give explicit diagnostics */
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int flgl; /* Report local return codes. */
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int rrc; /* recent return code */
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int crc; /* Cumulative return code */
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char rfs[8]; /* Return from section */
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#endif
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/*
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section s26, which pokes around at the hardware
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trying to figure out the characteristics of the machine that
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it is running on, saves information that is subsequently
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used by sections s626, s72, and s757. If this program is
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to be broken up into smallish pieces, say for running on
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a microcomputer, take care to see that s26 is called before
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calling any of the latter three sections.
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*/
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/*
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2.6 Hardware Characteristics
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*/
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#ifndef NO_OLD_FUNC_DECL
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s26(pd0)
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struct defs *pd0;
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{
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#else
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s26(struct defs *pd0) {
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#endif
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static char qs26[8] = "s26 ";
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char *ps, *pt;
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char c0, c1;
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#ifndef NO_FLOATS
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float temp, one, delta;
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double tempd, oned;
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#endif
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static char s[] = "%3d bits in %ss.\n";
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static char s2[] = "%e is the least number that can be added to 1. (%s).\n";
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ps = qs26;
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pt = pd0->rfs;
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while(*pt++ = *ps++);
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/* Here, we shake the machinery a little to see what falls
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out. First, we find out how many bits are in a char. */
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pd0->cbits = 0;
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c0 = 0;
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c1 = 1;
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while(c0 != c1) {
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c1 = c1<<1;
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pd0->cbits = pd0->cbits+1;
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}
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/* That information lets us determine the size of everything else. */
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pd0->ibits = pd0->cbits * sizeof(int);
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pd0->sbits = pd0->cbits * sizeof(short);
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pd0->lbits = pd0->cbits * sizeof(long);
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pd0->ubits = pd0->cbits * sizeof(unsigned);
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#ifndef NO_FLOATS
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pd0->fbits = pd0->cbits * sizeof(float);
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pd0->dbits = pd0->cbits * sizeof(double);
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#endif
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/* We have now almost reconstructed the table in section 2.6, the
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exception being the range of the floating point hardware.
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Now there are just so many ways to conjure up a floating point
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representation system that it's damned near impossible to guess
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what's going on by writing a program to interpret bit patterns.
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Further, the information isn't all that useful, if we consider
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the fact that machines that won't handle numbers between 10**30
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and 10**-30 are very hard to find, and that people playing with
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numbers outside that range have a lot more to worry about than
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just the capacity of the characteristic.
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A much more useful measure is the precision, which can be ex-
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pressed in terms of the smallest number that can be added to
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1. without loss of significance. We calculate that here, for
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float and double. */
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#ifndef NO_FLOATS
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one = 1.;
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delta = 1.;
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temp = 0.;
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while(temp != one) {
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temp = one+delta;
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delta = delta/2.;
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}
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pd0->fprec = delta * 4.;
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oned = 1.;
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delta = 1.;
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tempd = 0.;
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while(tempd != oned) {
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tempd = oned+delta;
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delta = delta/2.;
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}
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pd0->dprec = delta * 4.;
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#endif
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/* Now, if anyone's interested, we publish the results. */
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#ifndef CQ26_INCLUDED
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if(pd0->flgm != 0) {
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printf(s,pd0->cbits,"char");
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printf(s,pd0->ibits,"int");
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printf(s,pd0->sbits,"short");
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printf(s,pd0->lbits,"long");
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printf(s,pd0->ubits,"unsigned");
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printf(s,pd0->fbits,"float");
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printf(s,pd0->dbits,"double");
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#ifndef NO_FLOATS
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printf(s2,pd0->fprec,"float");
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printf(s2,pd0->dprec,"double");
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#else
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printf("NO_FLOATS\n");
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#endif
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}
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#endif
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/* Since we are only exploring and perhaps reporting, but not
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testing any features, we cannot return an error code. */
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return 0;
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}
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#ifndef CQ26_INCLUDED
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/*********************************************************************************************
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the main loop that launches the sections
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*********************************************************************************************/
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#ifndef NO_TYPELESS_STRUCT_PTR
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int section(int j,struct* pd0){
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#else
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int section(int j,void* pd0){
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#endif
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switch(j){
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case 0: return s26(pd0);
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}
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}
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#define cq_sections 1
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/*
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C REFERENCE MANUAL (main)
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*/
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#ifndef NO_OLD_FUNC_DECL
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main(n,args)
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int n;
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char **args;
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{
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#else
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int main(int n,char **args) {
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#endif
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int j;
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static struct defs d0, *pd0;
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d0.flgs = 1; /* These flags dictate */
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d0.flgm = 1; /* the verbosity of */
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d0.flgd = 1; /* the program. */
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d0.flgl = 1;
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pd0 = &d0;
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for (j=0; j<cq_sections; j++) {
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d0.rrc=section(j,pd0);
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d0.crc=d0.crc+d0.rrc;
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if(d0.flgs != 0) printf("Section %s returned %d.\n",d0.rfs,d0.rrc);
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}
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if(d0.crc == 0) printf("\nNo errors detected.\n");
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else printf("\nFailed.\n");
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return d0.crc;
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}
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#endif
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