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cc65/src/sp65/lynxsprite.c
Greg King a6b04f6e97 Changed most "backticks" (grave accents) into apostrophes. 
Quotations that are embraced by tick marks now look better, in most fonts.
2019-01-05 14:57:12 -05:00

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/*****************************************************************************/
/* */
/* lynxsprite.c */
/* */
/* Lynx sprite format backend for the sp65 sprite and bitmap utility */
/* */
/* */
/* */
/* (C) 2012, Ullrich von Bassewitz */
/* Roemerstrasse 52 */
/* D-70794 Filderstadt */
/* EMail: uz@cc65.org */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* warranty. In no event will the authors be held liable for any damages */
/* arising from the use of this software. */
/* */
/* Permission is granted to anyone to use this software for any purpose, */
/* including commercial applications, and to alter it and redistribute it */
/* freely, subject to the following restrictions: */
/* */
/* 1. The origin of this software must not be misrepresented; you must not */
/* claim that you wrote the original software. If you use this software */
/* in a product, an acknowledgment in the product documentation would be */
/* appreciated but is not required. */
/* 2. Altered source versions must be plainly marked as such, and must not */
/* be misrepresented as being the original software. */
/* 3. This notice may not be removed or altered from any source */
/* distribution. */
/* */
/*****************************************************************************/
#include <stdlib.h>
/* common */
#include "attrib.h"
#include "print.h"
/* sp65 */
#include "attr.h"
#include "error.h"
#include "lynxsprite.h"
/*****************************************************************************/
/* Data */
/*****************************************************************************/
/* Sprite mode */
enum Mode {
smAuto,
smLiteral,
smPacked,
smShaped
};
/*****************************************************************************/
/* Code */
/*****************************************************************************/
static enum Mode GetMode (const Collection* A)
/* Return the sprite mode from the attribute collection A */
{
/* Check for a mode attribute */
const char* Mode = GetAttrVal (A, "mode");
if (Mode) {
if (strcmp (Mode, "literal") == 0) {
return smLiteral;
} else if (strcmp (Mode, "packed") == 0) {
return smPacked;
} else if (strcmp (Mode, "shaped") == 0) {
return smShaped;
} else {
Error ("Invalid value for attribute 'mode'");
}
}
return smAuto;
}
static unsigned GetActionPointX (const Collection* A)
/* Return the sprite mode from the attribute collection A */
{
/* Check for a action point x attribute */
const char* ActionPointX = GetAttrVal (A, "ax");
if (ActionPointX) {
return atoi(ActionPointX);
} else {
return 0;
}
}
static unsigned GetActionPointY (const Collection* A)
/* Return the sprite mode from the attribute collection A */
{
/* Check for a action point y attribute */
const char* ActionPointY = GetAttrVal (A, "ay");
if (ActionPointY) {
return atoi(ActionPointY);
} else {
return 0;
}
}
static unsigned GetEdgeIndex (const Collection* A)
/* Return the sprite mode from the attribute collection A */
{
/* Get index for edge color in shaped mode */
const char* EdgeIndex = GetAttrVal (A, "edge");
if (EdgeIndex) {
return atoi(EdgeIndex);
} else {
return 0;
}
}
static char OutBuffer[512]; /* The maximum size is 508 pixels */
static unsigned char OutIndex;
static void AssembleByte(unsigned bits, char val)
{
static char bit_counter = 8, byte = 0;
/* initialize */
if (!bits) {
OutIndex = 0;
bit_counter = 8;
byte = 0;
return;
}
/* handle end of line */
if (bits == 8) {
if (bit_counter != 8) {
byte <<= bit_counter;
OutBuffer[OutIndex++] = byte;
if (!OutIndex) {
Error ("Sprite is too large for the Lynx");
}
if (byte & 0x1) {
OutBuffer[OutIndex++] = byte;
if (!OutIndex) {
Error ("Sprite is too large for the Lynx");
}
}
}
return;
}
/* handle end of line for literal */
if (bits == 7) {
if (bit_counter != 8) {
byte <<= bit_counter;
OutBuffer[OutIndex++] = byte;
if (!OutIndex) {
Error ("Sprite is too large for the Lynx");
}
}
return;
}
val <<= 8 - bits;
do {
byte <<= 1;
if (val & 0x80)
++byte;
if (!(--bit_counter)) {
OutBuffer[OutIndex++] = byte;
if (!OutIndex) {
Error ("Sprite is too large for the Lynx");
}
byte = 0;
bit_counter = 8;
}
val <<= 1;
} while (--bits);
}
static unsigned char ChoosePackagingMode(signed len, signed index, char ColorBits, char LineBuffer[512])
{
--len;
if (!len) {
return 0;
}
if (LineBuffer[index] != LineBuffer[index + 1]) {
return 0;
}
if (ColorBits > 2) {
return 1;
}
if (LineBuffer[index] != LineBuffer[index + 2]) {
return 0;
}
if (ColorBits > 1) {
return 1;
}
if (LineBuffer[index] != LineBuffer[index + 3]) {
return 0;
}
return 1;
}
static void WriteOutBuffer(StrBuf *D)
{
signed i;
/* Fix bug in Lynx where the count cannot be 1 */
if (OutIndex == 1) {
OutBuffer[OutIndex++] = 0;
}
/* Write the byte count to the end of the scanline */
if (OutIndex == 255) {
Error ("Sprite is too large for the Lynx");
}
SB_AppendChar (D, OutIndex+1);
/* Write scanline data */
for (i = 0; i < OutIndex; i++) {
SB_AppendChar (D, OutBuffer[i]);
}
}
static void encodeSprite(StrBuf *D, enum Mode M, char ColorBits, char ColorMask, char LineBuffer[512],
int len, int LastOpaquePixel) {
/*
** The data starts with a byte count. It tells the number of bytes on this
** line + 1.
** Special case is a count of 1. It will change to next quadrant.
** Other special case is 0. It will end the sprite.
**
** Ordinary data packet. These are bits in a stream.
** 1=literal 0=packed
** 4 bit count (+1)
** for literal you put "count" values
** for packed you repeat the value "count" times
** Never use packed mode for one pixel
** If the last bit on a line is 1 you need to add a byte of zeroes
** A sequence 00000 ends a scan line
**
** All data is high nybble first
*/
unsigned char V = 0;
signed i;
signed count;
unsigned char differ[16];
unsigned char *d_ptr;
AssembleByte(0, 0);
switch (M) {
case smAuto:
case smLiteral:
for (i = 0; i < len; i++) {
/* Fetch next pixel index into pixel buffer */
AssembleByte(ColorBits, LineBuffer[i] & ColorMask);
}
AssembleByte(7, 0);
/* Write the buffer to file */
WriteOutBuffer(D);
break;
case smPacked:
i = 0;
while (len) {
if (ChoosePackagingMode(len, i, ColorBits, LineBuffer)) {
/* Make runlength packet */
V = LineBuffer[i];
++i;
--len;
count = 0;
do {
++count;
++i;
--len;
} while (V == LineBuffer[i] && len && count != 15);
AssembleByte(5, count);
AssembleByte(ColorBits, V);
} else {
/* Make packed literal packet */
d_ptr = differ;
V = LineBuffer[i++];
*d_ptr++ = V;
--len;
count = 0;
while (ChoosePackagingMode(len, i, ColorBits, LineBuffer) == 0 && len && count != 15) {
V = LineBuffer[i++];
*d_ptr++ = V;
++count;
--len;
}
AssembleByte(5, count | 0x10);
d_ptr = differ;
do {
AssembleByte(ColorBits, *d_ptr++);
} while (--count >= 0);
}
}
AssembleByte(8, 0);
/* Write the buffer to file */
WriteOutBuffer(D);
break;
case smShaped:
if (LastOpaquePixel > -1) {
if (LastOpaquePixel < len - 1) {
len = LastOpaquePixel + 1;
}
i = 0;
while (len) {
if (ChoosePackagingMode(len, i, ColorBits, LineBuffer)) {
/* Make runlength packet */
V = LineBuffer[i];
++i;
--len;
count = 0;
do {
++count;
++i;
--len;
} while (V == LineBuffer[i] && len && count != 15);
AssembleByte(5, count);
AssembleByte(ColorBits, V);
} else {
/* Make packed literal packet */
d_ptr = differ;
V = LineBuffer[i++];
*d_ptr++ = V;
--len;
count = 0;
while (ChoosePackagingMode(len, i, ColorBits, LineBuffer) == 0 && len && count != 15) {
V = LineBuffer[i++];
*d_ptr++ = V;
++count;
--len;
}
AssembleByte(5, count | 0x10);
d_ptr = differ;
do {
AssembleByte(ColorBits, *d_ptr++);
} while (--count >= 0);
}
}
AssembleByte(5, 0);
AssembleByte(8, 0);
/* Write the buffer to file */
WriteOutBuffer(D);
}
break;
}
}
StrBuf* GenLynxSprite (const Bitmap* B, const Collection* A)
/* Generate binary output in Lynx sprite format for the bitmap B. The output
** is stored in a string buffer (which is actually a dynamic char array) and
** returned.
**
** The Lynx will draw 4 quadrants:
** - Down right
** - Up right
** - Up left
** - Down left
**
** The sprite will end with a byte 0.
*/
{
enum Mode M;
StrBuf* D;
signed X, Y;
unsigned OX, OY;
char ColorBits;
char ColorMask;
char EdgeIndex;
/* Get EdgeIndex */
EdgeIndex = GetEdgeIndex (A);
/* Action point of the sprite */
OX = GetActionPointX (A);
OY = GetActionPointY (A);
if (OX >= GetBitmapWidth (B)) {
Error ("Action point X cannot be larger than bitmap width");
}
if (OY >= GetBitmapHeight (B)) {
Error ("Action point Y cannot be larger than bitmap height");
}
/* Output the image properties */
Print (stdout, 1, "Image is %ux%u with %u colors%s\n",
GetBitmapWidth (B), GetBitmapHeight (B), GetBitmapColors (B),
BitmapIsIndexed (B)? " (indexed)" : "");
/* Get the sprite mode */
M = GetMode (A);
/* Now check if bitmap indexes are ok */
if (GetBitmapColors (B) > 16) {
Error ("Too many colors for a Lynx sprite");
}
ColorBits = 4;
ColorMask = 0x0f;
if (GetBitmapColors (B) < 9) {
ColorBits = 3;
ColorMask = 0x07;
}
if (GetBitmapColors (B) < 5) {
ColorBits = 2;
ColorMask = 0x03;
}
if (GetBitmapColors (B) < 3) {
ColorBits = 1;
ColorMask = 0x01;
}
/* Create the output buffer and resize it to the required size. */
D = NewStrBuf ();
SB_Realloc (D, 63);
/* Convert the image for quadrant bottom right */
for (Y = OY; Y < (signed)GetBitmapHeight (B); ++Y) {
signed i = 0;
signed LastOpaquePixel = -1;
char LineBuffer[512]; /* The maximum size is 508 pixels */
/* Fill the LineBuffer for easier optimisation */
for (X = OX; X < (signed)GetBitmapWidth (B); ++X) {
/* Fetch next bit into byte buffer */
LineBuffer[i] = GetPixel (B, X, Y).Index & ColorMask;
if (LineBuffer[i] != EdgeIndex) {
LastOpaquePixel = i;
}
++i;
}
encodeSprite(D, M, ColorBits, ColorMask, LineBuffer, i, LastOpaquePixel);
}
if ((OY == 0) && (OX == 0)) {
/* Trivial case only one quadrant */
/* Mark end of sprite */
SB_AppendChar (D, 0);
/* Return the converted bitmap */
return D;
}
/* Next quadrant */
SB_AppendChar (D, 1);
/* Convert the image for quadrant top right */
for (Y = OY - 1; Y >= 0; --Y) {
signed i = 0;
signed LastOpaquePixel = -1;
char LineBuffer[512]; /* The maximum size is 508 pixels */
/* Fill the LineBuffer for easier optimisation */
for (X = OX; X < (signed)GetBitmapWidth (B); ++X) {
/* Fetch next bit into byte buffer */
LineBuffer[i] = GetPixel (B, X, Y).Index & ColorMask;
if (LineBuffer[i] != EdgeIndex) {
LastOpaquePixel = i;
}
++i;
}
encodeSprite(D, M, ColorBits, ColorMask, LineBuffer, i, LastOpaquePixel);
}
if (OX == 0) {
/* Special case only two quadrants */
/* Mark end of sprite */
SB_AppendChar (D, 0);
/* Return the converted bitmap */
return D;
}
/* Next quadrant */
SB_AppendChar (D, 1);
/* Convert the image for quadrant top left */
for (Y = OY - 1; Y >= 0; --Y) {
signed i = 0;
signed LastOpaquePixel = -1;
char LineBuffer[512]; /* The maximum size is 508 pixels */
/* Fill the LineBuffer for easier optimisation */
for (X = OX - 1; X >= 0; --X) {
/* Fetch next bit into byte buffer */
LineBuffer[i] = GetPixel (B, X, Y).Index & ColorMask;
if (LineBuffer[i] != EdgeIndex) {
LastOpaquePixel = i;
}
++i;
}
encodeSprite(D, M, ColorBits, ColorMask, LineBuffer, i, LastOpaquePixel);
}
/* Next quadrant */
SB_AppendChar (D, 1);
/* Convert the image for quadrant bottom left */
for (Y = OY; Y < (signed)GetBitmapHeight (B); ++Y) {
signed i = 0;
signed LastOpaquePixel = -1;
char LineBuffer[512]; /* The maximum size is 508 pixels */
/* Fill the LineBuffer for easier optimisation */
for (X = OX - 1; X >= 0; --X) {
/* Fetch next bit into byte buffer */
LineBuffer[i] = GetPixel (B, X, Y).Index & ColorMask;
if (LineBuffer[i] != EdgeIndex) {
LastOpaquePixel = i;
}
++i;
}
encodeSprite(D, M, ColorBits, ColorMask, LineBuffer, i, LastOpaquePixel);
}
/* End sprite */
SB_AppendChar (D, 0);
/* Return the converted bitmap */
return D;
}
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