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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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vol_100
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170_01
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snap.c
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1979-12-31
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99 lines
/* Memory snapshot routine written in DeSmet 'C'.
by Stan Peters, 813 Clara, Palo Alto, 94303.
A debugging tool, useful for examining structures and file data.
It is also a valuable learning aid for 'C' but requires that
you have (or gain) dump reading ability.
It should have good portability, as it was first written in BDS 'C'
for a CP/M system. */
/* test of snap */
struct stype {
char line1[16];
char line2[16];
char line3[16];
char *p1;
char *p2;
char *p3;
char *p4;
} s;
char ss1[9];
char ss2[9];
int s1;
char ss3[9];
int s2;
int s3;
char *ss;
main()
{
for(s1 = 0; s1 <64 ;s1++)
s.line1[s1] = 1; /* initialize snap target */
strcpy(s.line2,"line2 string");
snap(s,32,"snap 1");
strcpy(s.line1,"too long line1 string");
snap(s,64,"snap 2");
strcpy (s.line3,s.line1);
s.p1 = s.line1;
s.p2 = &s.line1;
s.p3 = &s.p1; /* pointer to string pointer */
s.p4 = *s.p1; /* illogical, char to ptr */
snap(s,72,"snap 3");
strcpy(ss1,"1 string");
strcpy(ss2,"2 string");
strcpy(ss3,"3 string");
s1 = 1; s2 = 2; s3 = 3;
ss = &ss1;
snap(s,64,"snap 4");
}
/* routine displays memory as hex and characters */
char stst[80]; /* build space for snap line */
snap(ptr,len,label)
char *ptr; /* start of area to be snapped */
int len; /* length */
char *label;
{
char c;
int g, h, i, j, k, l, pl;
pl = ptr + len -1;
printf("\n%s", label);
for ( l = 0; l < len; l += 16)
{
for (g = 4; g < 80; g++)
stst[g] = ' '; /* clear line */
sprintf(stst,"\n%04x ",ptr); /* address of data */
i = 0; j = 7; k = 51;
for ( g=0; g<4; g++)
{
for ( h=0; h < 4 && pl >= ptr; h++)
{
c = *ptr++;
stst[j++] = makeasci(( c >> 4) & 0xf); /* left nibble */
stst[j++] = makeasci( c & 0xf); /* right nibble */
if (( c < ' ') || (c > 0x7e)) /* now character representation */
c = '.'; /* . if unprintable */
stst[k++] = c; /* print it */
}
j += 2; /* space after every four */
/* k++; insert this to space rt side chars */
}
stst[78] = 0;
puts(stst);
}
}
char makeasci(c)
short c;
{
return (( c > 9 ) ? c + 'A' - 10 : c + '0');
}