Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Use backtick code blocks for syntax highlighting

Browse source
This commit is contained in:
James Gregory 2013-12-31 11:38:48 +11:00
commit f658bfbb40
203 changed files with 26546 additions and 25801 deletions
Download patch file Download diff file Expand all files Collapse all files

70
39-02.md
View file

@ -45,45 +45,47 @@ equal 100.
**LISTING 39.1 L39-1.C**
/* Draws all pixels in the list of horizontal lines passed in, in
mode 13h, the VGA's 320x200 256-color mode. Uses memset to fill
each line, which is much faster than using DrawPixel but requires
that a large data model (compact, large, or huge) be in use when
running in real mode or 286 protected mode.
All C code tested with Borland C++. */
```c
/* Draws all pixels in the list of horizontal lines passed in, in
mode 13h, the VGA's 320x200 256-color mode. Uses memset to fill
each line, which is much faster than using DrawPixel but requires
that a large data model (compact, large, or huge) be in use when
running in real mode or 286 protected mode.
All C code tested with Borland C++. */
#include <string.h>
#include <dos.h>
#include "polygon.h"
#include <string.h>
#include <dos.h>
#include "polygon.h"
#define SCREEN_WIDTH 320
#define SCREEN_SEGMENT 0xA000
#define SCREEN_WIDTH 320
#define SCREEN_SEGMENT 0xA000
void DrawHorizontalLineList(struct HLineList * HLineListPtr,
int Color)
{
struct HLine *HLinePtr;
int Length, Width;
unsigned char far *ScreenPtr;
void DrawHorizontalLineList(struct HLineList * HLineListPtr,
int Color)
{
struct HLine *HLinePtr;
int Length, Width;
unsigned char far *ScreenPtr;
/* Point to the start of the first scan line on which to draw */
ScreenPtr = MK_FP(SCREEN_SEGMENT,
HLineListPtr->YStart * SCREEN_WIDTH);
/* Point to the start of the first scan line on which to draw */
ScreenPtr = MK_FP(SCREEN_SEGMENT,
HLineListPtr->YStart * SCREEN_WIDTH);
/* Point to the XStart/XEnd descriptor for the first (top)
horizontal line */
HLinePtr = HLineListPtr->HLinePtr;
/* Draw each horizontal line in turn, starting with the top one and
advancing one line each time */
Length = HLineListPtr->Length;
while (Length-- > 0) {
/* Draw the whole horizontal line if it has a positive width */
if ((Width = HLinePtr->XEnd - HLinePtr->XStart + 1) > 0)
memset(ScreenPtr + HLinePtr->XStart, Color, Width);
HLinePtr++; /* point to next scan line X info */
ScreenPtr += SCREEN_WIDTH; /* point to next scan line start */
}
}
/* Point to the XStart/XEnd descriptor for the first (top)
horizontal line */
HLinePtr = HLineListPtr->HLinePtr;
/* Draw each horizontal line in turn, starting with the top one and
advancing one line each time */
Length = HLineListPtr->Length;
while (Length-- > 0) {
/* Draw the whole horizontal line if it has a positive width */
if ((Width = HLinePtr->XEnd - HLinePtr->XStart + 1) > 0)
memset(ScreenPtr + HLinePtr->XStart, Color, Width);
HLinePtr++; /* point to next scan line X info */
ScreenPtr += SCREEN_WIDTH; /* point to next scan line start */
}
}
```
At this point, I'd like to mention that benchmarks are notoriously
unreliable; the results in Table 39.1 are accurate *only* for the test