Initial conversion to markdown
This commit is contained in:
James Gregory
parent
a96a114403
commit
5e10794a24
362 changed files with 67353 additions and 0 deletions
216
15-04.md
Normal file
216
15-04.md
Normal file
|
|
@ -0,0 +1,216 @@
|
|||
------------------------ --------------------------------- --------------------
|
||||
[Previous](15-03.html) [Table of Contents](index.html) [Next](16-01.html)
|
||||
------------------------ --------------------------------- --------------------
|
||||
|
||||
**LISTING 15.7 L15-7.ASM**
|
||||
|
||||
; C near-callable assembly function for inserting a new node in a
|
||||
; linked list sorted by ascending order of the Value field. The list
|
||||
; is circular; that is, it has a dummy node as both the head and the
|
||||
; tail of the list. The dummy node is a sentinel, containing the
|
||||
; largest possible Value field setting. Tested with TASM.
|
||||
MAX_TEXT_LENGTH equ 100 ;longest allowed Text field
|
||||
SENTINEL equ 32767 ;largest possible Value field
|
||||
LinkNode struc
|
||||
NextNode dw ?
|
||||
Value dw ?
|
||||
Text db MAX_TEXT_LENGTH+1 dup(?)
|
||||
;*** Any number of additional data fields may by present ***
|
||||
LinkNode ends
|
||||
|
||||
.model small
|
||||
.code
|
||||
|
||||
; Inserts the specified node into a ascending-value-sorted linked
|
||||
; list, such that value-sorting is maintained. Returns a pointer to
|
||||
; the node after which the new node is inserted.
|
||||
; C near-callable as:
|
||||
; struct LinkNode *InsertNodeSorted(struct LinkNode *HeadOfListNode,
|
||||
; struct LinkNode *NodeToInsert)
|
||||
parms struc
|
||||
dw 2 dup (?) ;pushed return address & BP
|
||||
HeadOfListNode dw ? ;pointer to head node of list
|
||||
NodeToInsert dw ? ;pointer to node to insert
|
||||
parms ends
|
||||
|
||||
public _InsertNodeSorted
|
||||
_InsertNodeSorted proc near
|
||||
push bp
|
||||
mov bp,sp ;point to stack frame
|
||||
push si ;preserve register vars
|
||||
push di
|
||||
mov si,[bp].NodeToInsert ;point to node to insert
|
||||
mov ax,[si].Value ;search value
|
||||
mov di,[bp].HeadOfListNode ;point to linked list in
|
||||
; which to insert
|
||||
SearchLoop:
|
||||
mov bx,di ;advance to the next node
|
||||
mov di,[bx].NextNode ;point to following node
|
||||
cmp [di].Value,ax ;is the following node's
|
||||
; value less than the value
|
||||
; from the node to insert?
|
||||
jl SearchLoop ;yes, so continue searching
|
||||
;no, so we have found our
|
||||
; insert point
|
||||
mov ax,[bx].NextNode ;link the new node between
|
||||
mov [si].NextNode,ax ; the current node and the
|
||||
mov [bx].NextNode,si ; following node
|
||||
mov ax,bx ;return pointer to node
|
||||
; after which we inserted
|
||||
pop di ;restore register vars
|
||||
pop si
|
||||
pop bp
|
||||
ret
|
||||
_InsertNodeSorted endp
|
||||
end
|
||||
|
||||
**LISTING 15.8 L15-8.C**
|
||||
|
||||
/* Sample linked list program. Tested with Borland C++. */
|
||||
#include <stdlib.h>
|
||||
#include <stdio.h>
|
||||
#include <conio.h>
|
||||
#include <ctype.h>
|
||||
#include <string.h>
|
||||
#include “llist.h”
|
||||
|
||||
void main()
|
||||
{ int Done = 0, Char, TempValue;
|
||||
struct LinkNode *TempPtr, *ListPtr, *TempPtr2;
|
||||
char TempBuffer[MAX_TEXT_LENGTH+3];
|
||||
|
||||
if ((ListPtr = InitLinkedList()) == NULL) {
|
||||
printf(“Out of memory\n”);
|
||||
exit(1);
|
||||
}
|
||||
while (!Done) {
|
||||
printf(“\nA=add; D=delete; F=find; L=list all; Q=quit\n>”);
|
||||
Char = toupper(getche());
|
||||
printf(“\n”);
|
||||
switch (Char) {
|
||||
case 'A': /* add a node */
|
||||
if ((TempPtr = malloc(sizeof(struct LinkNode))) == NULL)
|
||||
{
|
||||
printf(“Out of memory\n );
|
||||
exit(1);
|
||||
}
|
||||
printf(“Node value: ”);
|
||||
scanf(“%d”, &TempPtr->Value);
|
||||
if ((FindNodeBeforeValue(ListPtr,TempPtr->Value))!=NULL)
|
||||
{ printf(“*** value already in list; try again ***\n”);
|
||||
free(TempPtr);
|
||||
} else {printf(“Node text: ”);
|
||||
TempBuffer[0] = MAX_TEXT_LENGTH;
|
||||
cgets(TempBuffer);
|
||||
strcpy(TempPtr->Text, &TempBuffer[2]);
|
||||
InsertNodeSorted(ListPtr, TempPtr);
|
||||
printf(“\n”);
|
||||
}
|
||||
break;
|
||||
case 'D': /* delete a node */
|
||||
printf(“Value field of node to delete: ”);
|
||||
scanf(“%d”, &TempValue);
|
||||
if ((TempPtr = FindNodeBeforeValue(ListPtr, TempValue))
|
||||
!= NULL) {
|
||||
TempPtr2 = TempPtr->NextNode; /* -> node to delete */
|
||||
DeleteNodeAfter(TempPtr); /* delete it */
|
||||
free(TempPtr2); /* free its memory */
|
||||
} else {
|
||||
printf(“*** no such value field in list ***\n”)
|
||||
break;
|
||||
case 'F': /* find a node */
|
||||
printf(“Value field of node to find: ”);
|
||||
scanf(“%d”, &TempValue);
|
||||
if ((TempPtr = FindNodeBeforeValue(ListPtr, TempValue))
|
||||
!= NULL)
|
||||
printf(“Value: %d\nText: %s\n”,
|
||||
TempPtr->NextNode->Value, TempPtr->NextNode->Text);
|
||||
else
|
||||
printf(“*** no such value field in list ***\n”);
|
||||
break;
|
||||
case 'L': /* list all nodes */
|
||||
TempPtr = ListPtr->NextNode; /* point to first node */
|
||||
if (TempPtr == ListPtr) { /* empty if at sentinel */
|
||||
printf(“*** List is empty ***\n”);
|
||||
} else {
|
||||
do {printf(“Value: %d\n Text: %s\n”, TempPtr->Value,
|
||||
TempPtr->Text);
|
||||
TempPtr = TempPtr->NextNode;
|
||||
} while (TempPtr != ListPtr);
|
||||
}
|
||||
break;
|
||||
case 'Q':
|
||||
Done = 1;
|
||||
break;
|
||||
default:
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
### Hi/Lo in 24 Bytes {#Heading6}
|
||||
|
||||
In one of my *PC TECHNIQUES* “Pushing the Envelope” columns, I passed
|
||||
along one of David Stafford’s fiendish programming puzzles: Write a
|
||||
C-callable function to find the greatest or smallest unsigned **int**.
|
||||
Not a big deal—except that David had *already* done it in 24 bytes, so
|
||||
the challenge was to do it in 24 bytes or less.
|
||||
|
||||
Such routines soon began coming at me from all angles. However (and I
|
||||
hate to say this because some of my correspondents were *very* pleased
|
||||
with the thought that they had bested David), no one has yet met the
|
||||
challenge—because most of you folks missed a key point. When David said,
|
||||
“Write a function to find the greatest or smallest unsigned **int** in
|
||||
24 bytes or less,” he meant, “Write the **hi** and the **lo** functions
|
||||
in 24 bytes or less—*combined*.”
|
||||
|
||||
Oh.
|
||||
|
||||
Yes, a 24-byte hi/lo function is possible, anatomically improbable as it
|
||||
might seem. Which I guess goes to show that when one of David’s puzzles
|
||||
seems less than impossible, odds are you’re missing something. Listing
|
||||
15.9 is David’s 24-byte solution, from which a lot may be learned if one
|
||||
reads closely enough.
|
||||
|
||||
**LISTING 15.9 L15-9.ASM**
|
||||
|
||||
; Find the greatest or smallest unsigned int.
|
||||
; C callable (small model); 24 bytes.
|
||||
; By David Stafford.
|
||||
; unsigned hi( int num, unsigned a[] );
|
||||
; unsigned lo( int num, unsigned a[] );
|
||||
|
||||
public _hi, _lo
|
||||
|
||||
_hi: db 0b9h ;mov cx,immediate
|
||||
_lo: xor cx,cx
|
||||
pop ax ;get return address
|
||||
pop dx ;get count
|
||||
pop bx ;get pointer
|
||||
push bx ;restore pointer
|
||||
push dx ;restore count
|
||||
push ax ;restore return address
|
||||
save: mov ax,[bx]
|
||||
top: cmp ax,[bx]
|
||||
jcxz around
|
||||
cmc
|
||||
around: ja save
|
||||
inc bx
|
||||
inc bx
|
||||
dec dx
|
||||
jnz top
|
||||
|
||||
ret
|
||||
|
||||
Before I end this chapter, let me say that I get a lot of feedback from
|
||||
my readers, and it’s much appreciated. Keep those cards, letters, and
|
||||
email messages coming. And if any of you know Jeannie Schweigert, have
|
||||
her drop me a line and let me know how she’s doing these days....
|
||||
|
||||
------------------------ --------------------------------- --------------------
|
||||
[Previous](15-03.html) [Table of Contents](index.html) [Next](16-01.html)
|
||||
------------------------ --------------------------------- --------------------
|
||||
|
||||
* * * * *
|
||||
|
||||
Graphics Programming Black Book © 2001 Michael Abrash
|
||||
Loading…
Reference in a new issue