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improve documentation on Amstrad CPC formats

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Thomas Bernard 2019-12-22 14:36:37 +01:00
parent 22b6c2439f
commit 7db529b5c8
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GPG Key ID: 0FF11B67A5C0863C
2 changed files with 91 additions and 37 deletions
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113
src/cpcformats.c
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@ -39,6 +39,25 @@
#include "gfx2mem.h"
#include "gfx2log.h"
/**
* @defgroup cpcformats Amstrad CPC/CPC+ picture formats
* @ingroup loadsaveformats
*
* Support for Amstrad CPC/CPC+ picture formats. The Amstrad CPC has
* 3 video modes :
* - mode 0 : 160x200 16 colors
* - mode 1 : 320x200 4 colors
* - mode 2 : 640x200 2 colors
*
* Supported formats :
* - GO1/GO2 : GraphOS
* - SCR : OCP Art Studio / iMPdraw v2 / etc.
* - CM5 : Mode 5 Viewer
* - PPH : Perfect Pix
*
* @{
*/
/**
* Test for SCR file (Amstrad CPC)
*
@ -619,58 +638,64 @@ void Load_SCR(T_IO_Context * context)
* - wide pixels are mode 0
* - tall pixels are mode 2
*
* Mode and palette are stored in a .PAL file.
* Mode and palette are stored in a .PAL file for compatibility
* with OCP Art studio.
*
* The picture color index should be 0-15,
* The CPC Hardware palette is expected to be set (indexes 64 to 95)
*
* @todo Add possibility to set R9, R12, R13 values
* If the picture is using overscan (more than 16384 bytes)
* we produce a iMPdraw v2 format autoloading file.
* see http://orgams.wikidot.com/le-format-impdraw-v2
*
* If the picture is not using overscan (standard resolutions,
* < 16384 screen buffer) a BASIC loader is saved.
*
* @todo Add possibility to set R9 value
* @todo Add OCP packing support
* @todo Add possibility to include AMSDOS header, with proper loading
* address guessed from r12/r13 values.
*/
void Save_SCR(T_IO_Context * context)
{
int i, j;
unsigned char* output;
unsigned long outsize = 0;
unsigned char r1 = 0;
unsigned char r1 = 0; // Horizontal Displayed. Standard value is 40 (=80 bytes)
int cpc_mode;
FILE* file;
int cpc_plus_pal = 0;
unsigned short load_address = 0xC000;
unsigned short load_address = 0xC000; // Standard CPC screen address
unsigned short exec_address = 0xC7D0;
int overscan;
byte cpc_hw_pal[16];
byte r12 = 0x0C | 0x30;
byte r12 = 0x0C | 0x30; // set Display Start Address at C000
byte r13 = 0;
switch(context->Ratio)
{
case PIXEL_WIDE:
case PIXEL_WIDE2:
cpc_mode = 0;
cpc_mode = 0; // 16 colors, 2 pixels per byte
overscan = (context->Width * context->Height) > (16384 * 2);
break;
case PIXEL_TALL:
case PIXEL_TALL2:
case PIXEL_TALL3:
cpc_mode = 2;
cpc_mode = 2; // 2 colors, 8 pixels per byte
overscan = (context->Width * context->Height) > (16384 * 8);
break;
default:
cpc_mode = 1;
cpc_mode = 1; // 4 colors, 4 pixels per byte
overscan = (context->Width * context->Height) > (16384 * 4);
break;
}
if (overscan)
{
// format iMP v2
load_address = 0x170;
load_address = 0x170; // BASIC program at 0x170
// picture at 0x200
r12 = 0x0C | (0x200 >> 9);
r13 = (0x200 >> 1) & 0xff;
exec_address = 0; // BASIC program !
exec_address = 0; // BASIC program
}
CPC_set_HW_palette(context->Palette + 0x40);
@ -1105,7 +1130,8 @@ void Test_CM5(T_IO_Context * context, FILE * file)
* Load Amstrad CPC "Mode 5" picture
*
* Only support 288x256 resolution as the Mode 5 Viewer app only handles this
* single resoltion.
* single resolution.
* see https://www.cpc-power.com/index.php?page=detail&num=12905
*/
void Load_CM5(T_IO_Context* context)
{
@ -1247,19 +1273,28 @@ void Load_CM5(T_IO_Context* context)
}
/**
* Save a CPC Mode 5 picture.
* Resolution is fixed to 288x256.
* The pictures uses 5 layers. 4 for defining the "inks"
* the 5th to select one of the 4 inks.
*
* - Layer 1 : 1 color Only
* - Layer 2 and 3 : 1 color/line
* - Layer 4 : 1 color / 48x1 block
* - Layer 5 : CPC mode 2 288x256 picture.
*
* The .CM5 file contains the inks from layers 1-4,
* the .GFX file contains the pixel data in linear fashion
* @todo Check picture has 5 layers
* @todo Check the constraints on the layers
* @see https://www.cpc-power.com/index.php?page=detail&num=12905
*/
void Save_CM5(T_IO_Context* context)
{
FILE* file;
int tx, ty;
// TODO: Check picture has 5 layers
// TODO: Check the constraints on the layers
// Layer 1 : 1 color Only
// Layer 2 and 3 : 1 color/line
// Layer 4 : 1 color / 48x1 block
// TODO: handle filesize
if (!(file = Open_file_write(context)))
{
File_error = 1;
@ -1320,21 +1355,22 @@ void Save_CM5(T_IO_Context* context)
}
/* Amstrad CPC 'PPH' for Perfect Pix.
// This is a format designed by Rhino.
// There are 3 modes:
// - Mode 'R': 1:1 pixels, 16 colors from the CPC 27 color palette.
// (this is implemented on CPC as two pictures with wide pixels, the "odd" one
// being shifted half a pixel to the right), and flipping)
// - Mode 'B0': wide pixels, up to 126 out of 378 colors.
// (this is implemented as two pictures with wide pixels, sharing the same 16
// color palette, and flipping)
// - Mode 'B1': 1:1 pixels, 1 fixed color, up to 34 palettes of 9 colors
// (actually 4 colors + flipping)
//
// - The standard CPC formats can also be encapsulated into a PPH file.
//
// http://www.pouet.net/prod.php?which=67770#c766959
/**
* Amstrad CPC 'PPH' for Perfect Pix.
* This is a format designed by Rhino.
* There are 3 modes:
* - Mode 'R': 1:1 pixels, 16 colors from the CPC 27 color palette.
* (this is implemented on CPC as two pictures with wide pixels, the "odd" one
* being shifted half a pixel to the right), and flipping)
* - Mode 'B0': wide pixels, up to 126 out of 378 colors.
* (this is implemented as two pictures with wide pixels, sharing the same 16
* color palette, and flipping)
* - Mode 'B1': 1:1 pixels, 1 fixed color, up to 34 palettes of 9 colors
* (actually 4 colors + flipping)
*
* - The standard CPC formats can also be encapsulated into a PPH file.
*
* @see http://www.pouet.net/prod.php?which=67770#c766959
*/
void Test_PPH(T_IO_Context * context, FILE * file)
{
@ -1697,6 +1733,9 @@ void Load_PPH(T_IO_Context* context)
File_error = 0;
}
/**
* Not yet implemented
*/
void Save_PPH(T_IO_Context* context)
{
(void)context; // unused
@ -1713,3 +1752,5 @@ void Save_PPH(T_IO_Context* context)
// R: use 16 used colors (or 16 first?)
// B1: find the 16 colors used in a line? Or assume they are in-order already?
}
/* @} */

13
src/helpfile.h
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@ -2357,6 +2357,19 @@ static const T_Help_table helptable_save[] =
HELP_TEXT (" 1 background color common to the line,")
HELP_TEXT (" 1 color common for the 4x8 block and")
HELP_TEXT (" 2 specific colors.")
HELP_TEXT ("")
HELP_TEXT ("")
HELP_TITLE("AMSTRAD CPC FORMATS")
HELP_TEXT ("GrafX2 supports saving in various formats :")
HELP_TEXT ("- GraphOS (GO1/GO2/KIT) format only supports")
HELP_TEXT (" mode 0 192x272 16 CPC+ colors pictures")
HELP_TEXT ("- cpc (.SCR) saver detects mode from pixel")
HELP_TEXT (" ratio. \"Autoloading\" files are produced")
HELP_TEXT (" using iMPdraw v2 format for overscan or")
HELP_TEXT (" maintaining OCP compatibility for std res.")
HELP_TEXT ("- CM5 are specific 5 layer 288x256 pics for")
HELP_TEXT (" the \"Mode 5 Viewer\" software by SYX.")
//HELP_TEXT ("0----5----0----5----0----5----0----5----0--X")
};
static const T_Help_table helptable_load[] =
{