/**

 * $Id: rendcore.c,v 1.14 2007-01-26 01:37:39 nkeynes Exp $

 *

 * PVR2 renderer core.

 *

 * Copyright (c) 2005 Nathan Keynes.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

#include <sys/time.h>

#include "pvr2/pvr2.h"

#include "asic.h"

int pvr2_poly_depthmode[8] = { GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL,

				      GL_GREATER, GL_NOTEQUAL, GL_GEQUAL, 

				      GL_ALWAYS };

int pvr2_poly_srcblend[8] = { 

    GL_ZERO, GL_ONE, GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR,

    GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA, 

    GL_ONE_MINUS_DST_ALPHA };

int pvr2_poly_dstblend[8] = {

    GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR,

    GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA,

    GL_ONE_MINUS_DST_ALPHA };

int pvr2_poly_texblend[4] = {

    GL_REPLACE, 

    GL_MODULATE,  

    GL_DECAL, 

    GL_MODULATE 

};

int pvr2_render_colour_format[8] = {

    COLFMT_ARGB1555, COLFMT_RGB565, COLFMT_ARGB4444, COLFMT_ARGB1555,

    COLFMT_RGB888, COLFMT_ARGB8888, COLFMT_ARGB8888, COLFMT_ARGB4444 };

#define CULL_NONE 0

#define CULL_SMALL 1

#define CULL_CCW 2

#define CULL_CW 3

#define SEGMENT_END         0x80000000

#define SEGMENT_ZCLEAR      0x40000000

#define SEGMENT_SORT_TRANS  0x20000000

#define SEGMENT_START       0x10000000

#define SEGMENT_X(c)        (((c) >> 2) & 0x3F)

#define SEGMENT_Y(c)        (((c) >> 8) & 0x3F)

#define NO_POINTER          0x80000000

extern char *video_base;

gboolean pvr2_force_fragment_alpha = FALSE;

struct tile_segment {

    uint32_t control;

    pvraddr_t opaque_ptr;

    pvraddr_t opaquemod_ptr;

    pvraddr_t trans_ptr;

    pvraddr_t transmod_ptr;

    pvraddr_t punchout_ptr;

};

/**

 * Convert a half-float (16-bit) FP number to a regular 32-bit float.

 * Source is 1-bit sign, 5-bit exponent, 10-bit mantissa.

 * TODO: Check the correctness of this.

 */

float halftofloat( uint16_t half )

{

    union {

        float f;

        uint32_t i;

    } temp;

    /* int e = ((half & 0x7C00) >> 10) - 15 + 127;

    temp.i = ((half & 0x8000) << 16) | (e << 23) |

    ((half & 0x03FF) << 13); */

    temp.i = ((uint32_t)half)<<16;

    return temp.f;

}

/**

 * Setup the GL context for the supplied polygon context.

 * @param context pointer to 3 or 5 words of polygon context

 * @param modified boolean flag indicating that the modified

 *  version should be used, rather than the normal version.

 */

void render_set_context( uint32_t *context, int render_mode )

{

    uint32_t poly1 = context[0], poly2, texture;

    if( render_mode == RENDER_FULLMOD ) {

	poly2 = context[3];

	texture = context[4];

    } else {

	poly2 = context[1];

	texture = context[2];

    }

    if( POLY1_DEPTH_ENABLE(poly1) ) {

	glEnable( GL_DEPTH_TEST );

	glDepthFunc( POLY1_DEPTH_MODE(poly1) );

    } else {

	glDisable( GL_DEPTH_TEST );

    }

    switch( POLY1_CULL_MODE(poly1) ) {

    case CULL_NONE:

    case CULL_SMALL:

	glDisable( GL_CULL_FACE );

	break;

    case CULL_CCW:

	glEnable( GL_CULL_FACE );

	glFrontFace( GL_CW );

	break;

    case CULL_CW:

	glEnable( GL_CULL_FACE );

	glFrontFace( GL_CCW );

	break;

    }

    if( POLY1_SPECULAR(poly1) ) {

	glEnable(GL_COLOR_SUM);

    } else {

	glDisable(GL_COLOR_SUM);

    }

    if( POLY1_TEXTURED(poly1) ) {

	int width = POLY2_TEX_WIDTH(poly2);

	int height = POLY2_TEX_HEIGHT(poly2);

	glEnable(GL_TEXTURE_2D);

	texcache_get_texture( (texture&0x000FFFFF)<<3, width, height, texture );

	glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, POLY2_TEX_BLEND(poly2) );

	if( POLY2_TEX_CLAMP_U(poly2) ) {

	    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP );

	} else {

	    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );

	}	    

	if( POLY2_TEX_CLAMP_V(poly2) ) {

	    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP );

	} else {

	    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );

	}

    } else {

	glDisable( GL_TEXTURE_2D );

    }

    glShadeModel( POLY1_SHADE_MODEL(poly1) );

    int srcblend = POLY2_SRC_BLEND(poly2);

    int destblend = POLY2_DEST_BLEND(poly2);

    glBlendFunc( srcblend, destblend );

    if( POLY2_SRC_BLEND_TARGET(poly2) || POLY2_DEST_BLEND_TARGET(poly2) ) {

	ERROR( "Accumulation buffer not supported" );

    }

    pvr2_force_fragment_alpha = POLY2_ALPHA_ENABLE(poly2) ? FALSE : TRUE;

}

#define FARGB_A(x) (((float)(((x)>>24)+1))/256.0)

#define FARGB_R(x) (((float)((((x)>>16)&0xFF)+1))/256.0)

#define FARGB_G(x) (((float)((((x)>>8)&0xFF)+1))/256.0)

#define FARGB_B(x) (((float)(((x)&0xFF)+1))/256.0)

void render_unpack_vertexes( struct vertex_unpacked *out, uint32_t poly1, 

			     uint32_t *vertexes, int num_vertexes,

			     int vertex_size, int render_mode )

{

    int m = 0, i;

    if( render_mode == RENDER_FULLMOD ) {

	m = (vertex_size - 3)/2;

    }

    for( i=0; i<num_vertexes; i++ ) {

	float *vertexf = (float *)vertexes;

	int k = m + 3;

	out[i].x = vertexf[0];

	out[i].y = vertexf[1];

	out[i].z = vertexf[2];

    	if( POLY1_TEXTURED(poly1) ) {

	    if( POLY1_UV16(poly1) ) {

		out[i].u = halftofloat(vertexes[k]>>16);

		out[i].v = halftofloat(vertexes[k]);

		k++;

	    } else {

		out[i].u = vertexf[k];

		out[i].v = vertexf[k+1];

		k+=2;

	    }

	} else {

	    out[i].u = 0;

	    out[i].v = 0;

	}

	uint32_t argb = vertexes[k++];

	out[i].rgba[0] = FARGB_R(argb);

	out[i].rgba[1] = FARGB_G(argb);

        out[i].rgba[2] = FARGB_B(argb);

	out[i].rgba[3] = FARGB_A(argb);

	if( POLY1_SPECULAR(poly1) ) {

	    uint32_t offset = vertexes[k++];

	    out[i].offset_rgba[0] = FARGB_R(argb);

	    out[i].offset_rgba[1] = FARGB_G(argb);

	    out[i].offset_rgba[2] = FARGB_B(argb);

	    out[i].offset_rgba[3] = FARGB_A(argb);

	}

	vertexes += vertex_size;

    }

}

/**

 * Unpack the vertexes for a quad, calculating the values for the last

 * vertex.

 * FIXME: Integrate this with rendbkg somehow

 */

void render_unpack_quad( struct vertex_unpacked *unpacked, uint32_t poly1, 

			 uint32_t *vertexes, int vertex_size,

			 int render_mode )

{

    int i;

    struct vertex_unpacked diff0, diff1;

    render_unpack_vertexes( unpacked, poly1, vertexes, 3, vertex_size, render_mode );

    diff0.x = unpacked[0].x - unpacked[1].x;

    diff0.y = unpacked[0].y - unpacked[1].y;

    diff1.x = unpacked[2].x - unpacked[1].x;

    diff1.y = unpacked[2].y - unpacked[1].y;

    float detxy = ((diff1.y) * (diff0.x)) - ((diff0.y) * (diff1.x));

    float *vertexf = (float *)(vertexes+(vertex_size*3));

    if( detxy == 0 ) {

	memcpy( &unpacked[3], &unpacked[2], sizeof(struct vertex_unpacked) );

	unpacked[3].x = vertexf[0];

	unpacked[3].y = vertexf[1];

	return;

    }	

    unpacked[3].x = vertexf[0];

    unpacked[3].y = vertexf[1];

    float t = ((unpacked[3].x - unpacked[1].x) * diff1.y -

	       (unpacked[3].y - unpacked[1].y) * diff1.x) / detxy;

    float s = ((unpacked[3].y - unpacked[1].y) * diff0.x -

	       (unpacked[3].x - unpacked[1].x) * diff0.y) / detxy;

    diff0.z = (1/unpacked[0].z) - (1/unpacked[1].z);

    diff1.z = (1/unpacked[2].z) - (1/unpacked[1].z);

    unpacked[3].z = 1/((1/unpacked[1].z) + (t*diff0.z) + (s*diff1.z));

    diff0.u = unpacked[0].u - unpacked[1].u;

    diff0.v = unpacked[0].v - unpacked[1].v;

    diff1.u = unpacked[2].u - unpacked[1].u;

    diff1.v = unpacked[2].v - unpacked[1].v;

    unpacked[3].u = unpacked[1].u + (t*diff0.u) + (s*diff1.u);

    unpacked[3].v = unpacked[1].v + (t*diff0.v) + (s*diff1.v);

    if( !POLY1_GOURAUD_SHADED(poly1) ) {

	memcpy( unpacked[3].rgba, unpacked[2].rgba, sizeof(unpacked[2].rgba) );

	memcpy( unpacked[3].offset_rgba, unpacked[2].offset_rgba, sizeof(unpacked[2].offset_rgba) );

    } else {

	for( i=0; i<4; i++ ) {

	    float d0 = unpacked[0].rgba[i] - unpacked[1].rgba[i];

	    float d1 = unpacked[2].rgba[i] - unpacked[1].rgba[i];

	    unpacked[3].rgba[i] = unpacked[1].rgba[i] + (t*d0) + (s*d1);

	    d0 = unpacked[0].offset_rgba[i] - unpacked[1].offset_rgba[i];

	    d1 = unpacked[2].offset_rgba[i] - unpacked[1].offset_rgba[i];

	    unpacked[3].offset_rgba[i] = unpacked[1].offset_rgba[i] + (t*d0) + (s*d1);

	}

    }    

}

void render_unpacked_vertex_array( uint32_t poly1, struct vertex_unpacked *vertexes[], 

				   int num_vertexes ) {

    int i;

    glBegin( GL_TRIANGLE_STRIP );

    for( i=0; i<num_vertexes; i++ ) {

	if( POLY1_TEXTURED(poly1) ) {

	    glTexCoord2f( vertexes[i]->u, vertexes[i]->v );

	}

	if( pvr2_force_fragment_alpha ) {

	    glColor4f( vertexes[i]->rgba[0], vertexes[i]->rgba[1], vertexes[i]->rgba[2], 1.0 );

	} else {

	    glColor4f( vertexes[i]->rgba[0], vertexes[i]->rgba[1], vertexes[i]->rgba[2],

		       vertexes[i]->rgba[3] );

	}

	if( POLY1_SPECULAR(poly1) ) {

	    glSecondaryColor3fEXT( vertexes[i]->offset_rgba[0],

				   vertexes[i]->offset_rgba[1],

				   vertexes[i]->offset_rgba[2] );

	}

	glVertex3f( vertexes[i]->x, vertexes[i]->y, 1/vertexes[i]->z );

    }

    glEnd();

}

void render_quad_vertexes( uint32_t poly1, uint32_t *vertexes, int vertex_size, int render_mode )

{

    struct vertex_unpacked unpacked[4];

    struct vertex_unpacked *pt[4] = {&unpacked[0], &unpacked[1], &unpacked[3], &unpacked[2]};

    render_unpack_quad( unpacked, poly1, vertexes, vertex_size, render_mode );

    render_unpacked_vertex_array( poly1, pt, 4 );

}

void render_vertex_array( uint32_t poly1, uint32_t *vert_array[], int num_vertexes, int vertex_size,

			  int render_mode ) 

{

    int i, m=0;

    if( render_mode == RENDER_FULLMOD ) {

	m = (vertex_size - 3)/2;

    }

    glBegin( GL_TRIANGLE_STRIP );

    for( i=0; i<num_vertexes; i++ ) {

	uint32_t *vertexes = vert_array[i];

	float *vertexf = (float *)vert_array[i];

	uint32_t argb;

	int k = m + 3;

	if( POLY1_TEXTURED(poly1) ) {

	    if( POLY1_UV16(poly1) ) {

		glTexCoord2f( halftofloat(vertexes[k]>>16),

			      halftofloat(vertexes[k]) );

		k++;

	    } else {

		glTexCoord2f( vertexf[k], vertexf[k+1] );

		k+=2;

	    }

	}

	argb = vertexes[k++];

	if( pvr2_force_fragment_alpha ) {

	    glColor4ub( (GLubyte)(argb >> 16), (GLubyte)(argb >> 8), 

			(GLubyte)argb, 0xFF );

	} else {

	    glColor4ub( (GLubyte)(argb >> 16), (GLubyte)(argb >> 8), 

			(GLubyte)argb, (GLubyte)(argb >> 24) );

	}

	if( POLY1_SPECULAR(poly1) ) {

	    uint32_t spec = vertexes[k++];

	    glSecondaryColor3ubEXT( (GLubyte)(spec >> 16), (GLubyte)(spec >> 8), 

				 (GLubyte)spec );

	}

	glVertex3f( vertexf[0], vertexf[1], 1/vertexf[2] );

	vertexes += vertex_size;

    }

    glEnd();

}

void render_vertexes( uint32_t poly1, uint32_t *vertexes, int num_vertexes, int vertex_size,

		      int render_mode )

{

    uint32_t *vert_array[num_vertexes];

    int i;

    for( i=0; i<num_vertexes; i++ ) {

	vert_array[i] = vertexes;

	vertexes += vertex_size;

    }

    render_vertex_array( poly1, vert_array, num_vertexes, vertex_size, render_mode );

}

/**

 * Render a simple (not auto-sorted) tile

 */

void render_tile( pvraddr_t tile_entry, int render_mode, gboolean cheap_modifier_mode ) {

    uint32_t poly_bank = MMIO_READ(PVR2,RENDER_POLYBASE);

    uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

    do {

	uint32_t entry = *tile_list++;

	if( entry >> 28 == 0x0F ) {

	    break;

	} else if( entry >> 28 == 0x0E ) {

	    tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

	} else {

	    uint32_t *polygon = (uint32_t *)(video_base + poly_bank + ((entry & 0x000FFFFF) << 2));

	    int is_modified = entry & 0x01000000;

	    int vertex_length = (entry >> 21) & 0x07;

	    int context_length = 3;

	    if( is_modified && !cheap_modifier_mode ) {

		context_length = 5;

		vertex_length *= 2 ;

	    }

	    vertex_length += 3;

	    if( (entry & 0xE0000000) == 0x80000000 ) {

		/* Triangle(s) */

		int strip_count = ((entry >> 25) & 0x0F)+1;

		int polygon_length = 3 * vertex_length + context_length;

		int i;

		for( i=0; i<strip_count; i++ ) {

		    render_set_context( polygon, render_mode );

		    render_vertexes( *polygon, polygon+context_length, 3, vertex_length,

				     render_mode );

		    polygon += polygon_length;

		}

	    } else if( (entry & 0xE0000000) == 0xA0000000 ) {

		/* Sprite(s) */

		int strip_count = ((entry >> 25) & 0x0F)+1;

		int polygon_length = 4 * vertex_length + context_length;

		int i;

		for( i=0; i<strip_count; i++ ) {

		    render_set_context( polygon, render_mode );

		    render_quad_vertexes( *polygon, polygon+context_length, vertex_length,

					  render_mode );

		    polygon += polygon_length;

		}

	    } else {

		/* Polygon */

		int i, first=-1, last = -1;

		for( i=0; i<6; i++ ) {

		    if( entry & (0x40000000>>i) ) {

			if( first == -1 ) first = i;

			last = i;

		    }

		}

		if( first != -1 ) {

		    first = 0;

		    render_set_context(polygon, render_mode);

		    render_vertexes( *polygon, polygon+context_length + (first*vertex_length),

				     (last-first+3), vertex_length, render_mode );

		}

	    }

	}

    } while( 1 );

}

void pvr2_render_tilebuffer( int width, int height, int clipx1, int clipy1, 

			int clipx2, int clipy2 ) {

    pvraddr_t segmentbase = MMIO_READ( PVR2, RENDER_TILEBASE );

    int tile_sort;

    gboolean cheap_shadow;

    int obj_config = MMIO_READ( PVR2, RENDER_OBJCFG );

    int isp_config = MMIO_READ( PVR2, RENDER_ISPCFG );

    int shadow_cfg = MMIO_READ( PVR2, RENDER_SHADOW );

    if( (obj_config & 0x00200000) == 0 ) {

	if( isp_config & 1 ) {

	    tile_sort = 0;

	} else {

	    tile_sort = 2;

	}

    } else {

	tile_sort = 1;

    }

    cheap_shadow = shadow_cfg & 0x100 ? TRUE : FALSE;

    struct tile_segment *segment = (struct tile_segment *)(video_base + segmentbase);

    struct timeval tv_start, tv_end;

    gettimeofday(&tv_start, NULL);

    glEnable( GL_SCISSOR_TEST );

    do {

	// fwrite_dump32v( (uint32_t *)segment, sizeof(struct tile_segment), 6, stderr );

	int tilex = SEGMENT_X(segment->control);

	int tiley = SEGMENT_Y(segment->control);

	int x1 = tilex << 5;

	int y1 = tiley << 5;

	if( x1 + 32 <= clipx1 ||

	    y1 + 32 <= clipy1 ||

	    x1 >= clipx2 ||

	    y1 >= clipy2 ) {

	    /* Tile completely clipped, skip */

	    continue;

	}

	/* Set a scissor on the visible part of the tile */

	int w = MIN(x1+32, clipx2) - x1;

	int h = MIN(y1+32, clipy2) - y1;

	x1 = MAX(x1,clipx1);

	y1 = MAX(y1,clipy1);

	glScissor( x1, height-y1-h, w, h );

	if( (segment->opaque_ptr & NO_POINTER) == 0 ) {

	    if( (segment->opaquemod_ptr & NO_POINTER) == 0 ) {

		/* TODO */

	    }

	    render_tile( segment->opaque_ptr, RENDER_NORMAL, cheap_shadow );

	}

	if( (segment->trans_ptr & NO_POINTER) == 0 ) {

	    if( (segment->transmod_ptr & NO_POINTER) == 0 ) {

		/* TODO */

	    } 

	    if( tile_sort == 2 || 

		(tile_sort == 1 && ((segment->control & SEGMENT_SORT_TRANS)==0)) ) {

		render_autosort_tile( segment->trans_ptr, RENDER_NORMAL, cheap_shadow );

	    } else {

		render_tile( segment->trans_ptr, RENDER_NORMAL, cheap_shadow );

	    }

	}

	if( (segment->punchout_ptr & NO_POINTER) == 0 ) {

	    render_tile( segment->punchout_ptr, RENDER_NORMAL, cheap_shadow );

	}

    } while( ((segment++)->control & SEGMENT_END) == 0 );

    glDisable( GL_SCISSOR_TEST );

    gettimeofday(&tv_end, NULL);

    timersub(&tv_end,&tv_start, &tv_start);

}

static float render_find_maximum_tile_z( pvraddr_t tile_entry, float inputz )

{

    uint32_t poly_bank = MMIO_READ(PVR2,RENDER_POLYBASE);

    uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

    int shadow_cfg = MMIO_READ( PVR2, RENDER_SHADOW ) & 0x100;

    int i, j;

    float z = inputz;

    do {

	uint32_t entry = *tile_list++;

	if( entry >> 28 == 0x0F ) {

	    break;

	} else if( entry >> 28 == 0x0E ) {

	    tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

	} else {

	    uint32_t *polygon = (uint32_t *)(video_base + poly_bank + ((entry & 0x000FFFFF) << 2));

	    int is_modified = entry & 0x01000000;

	    int vertex_length = (entry >> 21) & 0x07;

	    int context_length = 3;

	    if( (entry & 0x01000000) && shadow_cfg ) {

		context_length = 5;

		vertex_length *= 2 ;

	    }

	    vertex_length += 3;

	    if( (entry & 0xE0000000) == 0x80000000 ) {

		/* Triangle(s) */

		int strip_count = ((entry >> 25) & 0x0F)+1;

		float *vertexz = (float *)(polygon+context_length+2);

		for( i=0; i<strip_count; i++ ) {

		    for( j=0; j<3; j++ ) {

			if( *vertexz > z ) {

			    z = *vertexz;

			}

			vertexz += vertex_length;

		    }

		    vertexz += context_length;

		}

	    } else if( (entry & 0xE0000000) == 0xA0000000 ) {

		/* Sprite(s) */

		int strip_count = ((entry >> 25) & 0x0F)+1;

		int polygon_length = 4 * vertex_length + context_length;

		int i;

		float *vertexz = (float *)(polygon+context_length+2);

		for( i=0; i<strip_count; i++ ) {

		    for( j=0; j<4; j++ ) {

			if( *vertexz > z ) {

			    z = *vertexz;

			}

			vertexz += vertex_length;

		    }

		    vertexz+=context_length;

		}

	    } else {

		/* Polygon */

		int i, first=-1, last = -1;

		float *vertexz = (float *)polygon+context_length+2;

		for( i=0; i<6; i++ ) {

		    if( (entry & (0x40000000>>i)) && *vertexz > z ) {

			z = *vertexz;

		    }

		    vertexz += vertex_length;

		}

	    }

	}

    } while(1);

    return z;

}

/**

 * Scan through the scene to determine the largest z value (in order to set up

 * an appropriate near clip plane).

 */

float pvr2_render_find_maximum_z( )

{

    pvraddr_t segmentbase = MMIO_READ( PVR2, RENDER_TILEBASE );

    float maximumz = MMIO_READF( PVR2, RENDER_FARCLIP ); /* Initialize to the far clip plane */

    struct tile_segment *segment = (struct tile_segment *)(video_base + segmentbase);

    do {

	if( (segment->opaque_ptr & NO_POINTER) == 0 ) {

	    maximumz = render_find_maximum_tile_z(segment->opaque_ptr, maximumz);

	}

	if( (segment->opaquemod_ptr & NO_POINTER) == 0 ) {

	    maximumz = render_find_maximum_tile_z(segment->opaquemod_ptr, maximumz);

	}

	if( (segment->trans_ptr & NO_POINTER) == 0 ) {

	    maximumz = render_find_maximum_tile_z(segment->trans_ptr, maximumz);

	}

	if( (segment->transmod_ptr & NO_POINTER) == 0 ) {

	    maximumz = render_find_maximum_tile_z(segment->transmod_ptr, maximumz);

	}

	if( (segment->punchout_ptr & NO_POINTER) == 0 ) {

	    maximumz = render_find_maximum_tile_z(segment->punchout_ptr, maximumz);

	}

    } while( ((segment++)->control & SEGMENT_END) == 0 );

    return 1/maximumz;

}