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dsp4.cpp
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dsp4.cpp
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/*****************************************************************************\
Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
This file is licensed under the Snes9x License.
For further information, consult the LICENSE file in the root directory.
\*****************************************************************************/
/*
Due recognition and credit are given on Overload's DSP website.
Thank those contributors for their hard work on this chip.
Fixed-point math reminder:
[sign, integer, fraction]
1.15.00 * 1.15.00 = 2.30.00 -> 1.30.00 (DSP) -> 1.31.00 (LSB is '0')
1.15.00 * 1.00.15 = 2.15.15 -> 1.15.15 (DSP) -> 1.15.16 (LSB is '0')
*/
#include "snes9x.h"
#include "memmap.h"
#define DSP4_CLEAR_OUT() \
{ DSP4.out_count = 0; DSP4.out_index = 0; }
#define DSP4_WRITE_BYTE(d) \
{ WRITE_WORD(DSP4.output + DSP4.out_count, (d)); DSP4.out_count++; }
#define DSP4_WRITE_WORD(d) \
{ WRITE_WORD(DSP4.output + DSP4.out_count, (d)); DSP4.out_count += 2; }
#ifndef MSB_FIRST
#define DSP4_WRITE_16_WORD(d) \
{ memcpy(DSP4.output + DSP4.out_count, (d), 32); DSP4.out_count += 32; }
#else
#define DSP4_WRITE_16_WORD(d) \
{ for (int p = 0; p < 16; p++) DSP4_WRITE_WORD((d)[p]); }
#endif
// used to wait for dsp i/o
#define DSP4_WAIT(x) \
DSP4.in_index = 0; DSP4.Logic = (x); return
// 1.7.8 -> 1.15.16
#define SEX78(a) (((int32) ((int16) (a))) << 8)
// 1.15.0 -> 1.15.16
#define SEX16(a) (((int32) ((int16) (a))) << 16)
static int16 DSP4_READ_WORD (void);
static int32 DSP4_READ_DWORD (void);
static int16 DSP4_Inverse (int16);
static void DSP4_Multiply (int16, int16, int32 *);
static void DSP4_OP01 (void);
static void DSP4_OP03 (void);
static void DSP4_OP05 (void);
static void DSP4_OP06 (void);
static void DSP4_OP07 (void);
static void DSP4_OP08 (void);
static void DSP4_OP09 (void);
static void DSP4_OP0A (int16, int16 *, int16 *, int16 *, int16 *);
static void DSP4_OP0B (bool8 *, int16, int16, int16, bool8, bool8);
static void DSP4_OP0D (void);
static void DSP4_OP0E (void);
static void DSP4_OP0F (void);
static void DSP4_OP10 (void);
static void DSP4_OP11 (int16, int16, int16, int16, int16 *);
static void DSP4_SetByte (void);
static void DSP4_GetByte (void);
static int16 DSP4_READ_WORD (void)
{
int16 out;
out = READ_WORD(DSP4.parameters + DSP4.in_index);
DSP4.in_index += 2;
return (out);
}
static int32 DSP4_READ_DWORD (void)
{
int32 out;
out = READ_DWORD(DSP4.parameters + DSP4.in_index);
DSP4.in_index += 4;
return (out);
}
static int16 DSP4_Inverse (int16 value)
{
// Attention: This lookup table is not verified
static const uint16 div_lut[64] =
{
0x0000, 0x8000, 0x4000, 0x2aaa, 0x2000, 0x1999, 0x1555, 0x1249,
0x1000, 0x0e38, 0x0ccc, 0x0ba2, 0x0aaa, 0x09d8, 0x0924, 0x0888,
0x0800, 0x0787, 0x071c, 0x06bc, 0x0666, 0x0618, 0x05d1, 0x0590,
0x0555, 0x051e, 0x04ec, 0x04bd, 0x0492, 0x0469, 0x0444, 0x0421,
0x0400, 0x03e0, 0x03c3, 0x03a8, 0x038e, 0x0375, 0x035e, 0x0348,
0x0333, 0x031f, 0x030c, 0x02fa, 0x02e8, 0x02d8, 0x02c8, 0x02b9,
0x02aa, 0x029c, 0x028f, 0x0282, 0x0276, 0x026a, 0x025e, 0x0253,
0x0249, 0x023e, 0x0234, 0x022b, 0x0222, 0x0219, 0x0210, 0x0208
};
// saturate bounds
if (value < 0)
value = 0;
if (value > 63)
value = 63;
return (div_lut[value]);
}
static void DSP4_Multiply (int16 Multiplicand, int16 Multiplier, int32 *Product)
{
*Product = (Multiplicand * Multiplier << 1) >> 1;
}
static void DSP4_OP01 (void)
{
DSP4.waiting4command = FALSE;
// op flow control
switch (DSP4.Logic)
{
case 1: goto resume1; break;
case 2: goto resume2; break;
case 3: goto resume3; break;
}
////////////////////////////////////////////////////
// process initial inputs
// sort inputs
DSP4.world_y = DSP4_READ_DWORD();
DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
DSP4.poly_top[0][0] = DSP4_READ_WORD();
DSP4.poly_cx[1][0] = DSP4_READ_WORD();
DSP4.viewport_bottom = DSP4_READ_WORD();
DSP4.world_x = DSP4_READ_DWORD();
DSP4.poly_cx[0][0] = DSP4_READ_WORD();
DSP4.poly_ptr[0][0] = DSP4_READ_WORD();
DSP4.world_yofs = DSP4_READ_WORD();
DSP4.world_dy = DSP4_READ_DWORD();
DSP4.world_dx = DSP4_READ_DWORD();
DSP4.distance = DSP4_READ_WORD();
DSP4_READ_WORD(); // 0x0000
DSP4.world_xenv = DSP4_READ_DWORD();
DSP4.world_ddy = DSP4_READ_WORD();
DSP4.world_ddx = DSP4_READ_WORD();
DSP4.view_yofsenv = DSP4_READ_WORD();
// initial (x, y, offset) at starting raster line
DSP4.view_x1 = (DSP4.world_x + DSP4.world_xenv) >> 16;
DSP4.view_y1 = DSP4.world_y >> 16;
DSP4.view_xofs1 = DSP4.world_x >> 16;
DSP4.view_yofs1 = DSP4.world_yofs;
DSP4.view_turnoff_x = 0;
DSP4.view_turnoff_dx = 0;
// first raster line
DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];
do
{
////////////////////////////////////////////////////
// process one iteration of projection
// perspective projection of world (x, y, scroll) points
// based on the current projection lines
DSP4.view_x2 = (((DSP4.world_x + DSP4.world_xenv) >> 16) * DSP4.distance >> 15) + (DSP4.view_turnoff_x * DSP4.distance >> 15);
DSP4.view_y2 = (DSP4.world_y >> 16) * DSP4.distance >> 15;
DSP4.view_xofs2 = DSP4.view_x2;
DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;
// 1. World x-location before transformation
// 2. Viewer x-position at the next
// 3. World y-location before perspective projection
// 4. Viewer y-position below the horizon
// 5. Number of raster lines drawn in this iteration
DSP4_CLEAR_OUT();
DSP4_WRITE_WORD((DSP4.world_x + DSP4.world_xenv) >> 16);
DSP4_WRITE_WORD(DSP4.view_x2);
DSP4_WRITE_WORD(DSP4.world_y >> 16);
DSP4_WRITE_WORD(DSP4.view_y2);
//////////////////////////////////////////////////////
// SR = 0x00
// determine # of raster lines used
DSP4.segments = DSP4.poly_raster[0][0] - DSP4.view_y2;
// prevent overdraw
if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
DSP4.segments = 0;
else
DSP4.poly_raster[0][0] = DSP4.view_y2;
// don't draw outside the window
if (DSP4.view_y2 < DSP4.poly_top[0][0])
{
DSP4.segments = 0;
// flush remaining raster lines
if (DSP4.view_y1 >= DSP4.poly_top[0][0])
DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
}
// SR = 0x80
DSP4_WRITE_WORD(DSP4.segments);
//////////////////////////////////////////////////////
// scan next command if no SR check needed
if (DSP4.segments)
{
int32 px_dx, py_dy;
int32 x_scroll, y_scroll;
// SR = 0x00
// linear interpolation (lerp) between projected points
px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;
// starting step values
x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);
// SR = 0x80
// rasterize line
for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
{
// 1. HDMA memory pointer (bg1)
// 2. vertical scroll offset ($210E)
// 3. horizontal scroll offset ($210D)
DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);
// update memory address
DSP4.poly_ptr[0][0] -= 4;
// update screen values
x_scroll += px_dx;
y_scroll += py_dy;
}
}
////////////////////////////////////////////////////
// Post-update
// update new viewer (x, y, scroll) to last raster line drawn
DSP4.view_x1 = DSP4.view_x2;
DSP4.view_y1 = DSP4.view_y2;
DSP4.view_xofs1 = DSP4.view_xofs2;
DSP4.view_yofs1 = DSP4.view_yofs2;
// add deltas for projection lines
DSP4.world_dx += SEX78(DSP4.world_ddx);
DSP4.world_dy += SEX78(DSP4.world_ddy);
// update projection lines
DSP4.world_x += (DSP4.world_dx + DSP4.world_xenv);
DSP4.world_y += DSP4.world_dy;
// update road turnoff position
DSP4.view_turnoff_x += DSP4.view_turnoff_dx;
////////////////////////////////////////////////////
// command check
// scan next command
DSP4.in_count = 2;
DSP4_WAIT(1);
resume1:
// check for termination
DSP4.distance = DSP4_READ_WORD();
if (DSP4.distance == -0x8000)
break;
// road turnoff
if ((uint16) DSP4.distance == 0x8001)
{
DSP4.in_count = 6;
DSP4_WAIT(2);
resume2:
DSP4.distance = DSP4_READ_WORD();
DSP4.view_turnoff_x = DSP4_READ_WORD();
DSP4.view_turnoff_dx = DSP4_READ_WORD();
// factor in new changes
DSP4.view_x1 += (DSP4.view_turnoff_x * DSP4.distance >> 15);
DSP4.view_xofs1 += (DSP4.view_turnoff_x * DSP4.distance >> 15);
// update stepping values
DSP4.view_turnoff_x += DSP4.view_turnoff_dx;
DSP4.in_count = 2;
DSP4_WAIT(1);
}
// already have 2 bytes read
DSP4.in_count = 6;
DSP4_WAIT(3);
resume3:
// inspect inputs
DSP4.world_ddy = DSP4_READ_WORD();
DSP4.world_ddx = DSP4_READ_WORD();
DSP4.view_yofsenv = DSP4_READ_WORD();
// no envelope here
DSP4.world_xenv = 0;
}
while (1);
// terminate op
DSP4.waiting4command = TRUE;
}
static void DSP4_OP03 (void)
{
DSP4.OAM_RowMax = 33;
memset(DSP4.OAM_Row, 0, 64);
}
static void DSP4_OP05 (void)
{
DSP4.OAM_index = 0;
DSP4.OAM_bits = 0;
memset(DSP4.OAM_attr, 0, 32);
DSP4.sprite_count = 0;
}
static void DSP4_OP06 (void)
{
DSP4_CLEAR_OUT();
DSP4_WRITE_16_WORD(DSP4.OAM_attr);
}
static void DSP4_OP07 (void)
{
DSP4.waiting4command = FALSE;
// op flow control
switch (DSP4.Logic)
{
case 1: goto resume1; break;
case 2: goto resume2; break;
}
////////////////////////////////////////////////////
// sort inputs
DSP4.world_y = DSP4_READ_DWORD();
DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
DSP4.poly_top[0][0] = DSP4_READ_WORD();
DSP4.poly_cx[1][0] = DSP4_READ_WORD();
DSP4.viewport_bottom = DSP4_READ_WORD();
DSP4.world_x = DSP4_READ_DWORD();
DSP4.poly_cx[0][0] = DSP4_READ_WORD();
DSP4.poly_ptr[0][0] = DSP4_READ_WORD();
DSP4.world_yofs = DSP4_READ_WORD();
DSP4.distance = DSP4_READ_WORD();
DSP4.view_y2 = DSP4_READ_WORD();
DSP4.view_dy = DSP4_READ_WORD() * DSP4.distance >> 15;
DSP4.view_x2 = DSP4_READ_WORD();
DSP4.view_dx = DSP4_READ_WORD() * DSP4.distance >> 15;
DSP4.view_yofsenv = DSP4_READ_WORD();
// initial (x, y, offset) at starting raster line
DSP4.view_x1 = DSP4.world_x >> 16;
DSP4.view_y1 = DSP4.world_y >> 16;
DSP4.view_xofs1 = DSP4.view_x1;
DSP4.view_yofs1 = DSP4.world_yofs;
// first raster line
DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];
do
{
////////////////////////////////////////////////////
// process one iteration of projection
// add shaping
DSP4.view_x2 += DSP4.view_dx;
DSP4.view_y2 += DSP4.view_dy;
// vertical scroll calculation
DSP4.view_xofs2 = DSP4.view_x2;
DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;
// 1. Viewer x-position at the next
// 2. Viewer y-position below the horizon
// 3. Number of raster lines drawn in this iteration
DSP4_CLEAR_OUT();
DSP4_WRITE_WORD(DSP4.view_x2);
DSP4_WRITE_WORD(DSP4.view_y2);
//////////////////////////////////////////////////////
// SR = 0x00
// determine # of raster lines used
DSP4.segments = DSP4.view_y1 - DSP4.view_y2;
// prevent overdraw
if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
DSP4.segments = 0;
else
DSP4.poly_raster[0][0] = DSP4.view_y2;
// don't draw outside the window
if (DSP4.view_y2 < DSP4.poly_top[0][0])
{
DSP4.segments = 0;
// flush remaining raster lines
if (DSP4.view_y1 >= DSP4.poly_top[0][0])
DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
}
// SR = 0x80
DSP4_WRITE_WORD(DSP4.segments);
//////////////////////////////////////////////////////
// scan next command if no SR check needed
if (DSP4.segments)
{
int32 px_dx, py_dy;
int32 x_scroll, y_scroll;
// SR = 0x00
// linear interpolation (lerp) between projected points
px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;
// starting step values
x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);
// SR = 0x80
// rasterize line
for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
{
// 1. HDMA memory pointer (bg2)
// 2. vertical scroll offset ($2110)
// 3. horizontal scroll offset ($210F)
DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);
// update memory address
DSP4.poly_ptr[0][0] -= 4;
// update screen values
x_scroll += px_dx;
y_scroll += py_dy;
}
}
/////////////////////////////////////////////////////
// Post-update
// update new viewer (x, y, scroll) to last raster line drawn
DSP4.view_x1 = DSP4.view_x2;
DSP4.view_y1 = DSP4.view_y2;
DSP4.view_xofs1 = DSP4.view_xofs2;
DSP4.view_yofs1 = DSP4.view_yofs2;
////////////////////////////////////////////////////
// command check
// scan next command
DSP4.in_count = 2;
DSP4_WAIT(1);
resume1:
// check for opcode termination
DSP4.distance = DSP4_READ_WORD();
if (DSP4.distance == -0x8000)
break;
// already have 2 bytes in queue
DSP4.in_count = 10;
DSP4_WAIT(2);
resume2:
// inspect inputs
DSP4.view_y2 = DSP4_READ_WORD();
DSP4.view_dy = DSP4_READ_WORD() * DSP4.distance >> 15;
DSP4.view_x2 = DSP4_READ_WORD();
DSP4.view_dx = DSP4_READ_WORD() * DSP4.distance >> 15;
DSP4.view_yofsenv = DSP4_READ_WORD();
}
while (1);
DSP4.waiting4command = TRUE;
}
static void DSP4_OP08 (void)
{
int16 win_left, win_right;
int16 view_x[2], view_y[2];
int16 envelope[2][2];
DSP4.waiting4command = FALSE;
// op flow control
switch (DSP4.Logic)
{
case 1: goto resume1; break;
case 2: goto resume2; break;
}
////////////////////////////////////////////////////
// process initial inputs for two polygons
// clip values
DSP4.poly_clipRt[0][0] = DSP4_READ_WORD();
DSP4.poly_clipRt[0][1] = DSP4_READ_WORD();
DSP4.poly_clipRt[1][0] = DSP4_READ_WORD();
DSP4.poly_clipRt[1][1] = DSP4_READ_WORD();
DSP4.poly_clipLf[0][0] = DSP4_READ_WORD();
DSP4.poly_clipLf[0][1] = DSP4_READ_WORD();
DSP4.poly_clipLf[1][0] = DSP4_READ_WORD();
DSP4.poly_clipLf[1][1] = DSP4_READ_WORD();
// unknown (constant) (ex. 1P/2P = $00A6, $00A6, $00A6, $00A6)
DSP4_READ_WORD();
DSP4_READ_WORD();
DSP4_READ_WORD();
DSP4_READ_WORD();
// unknown (constant) (ex. 1P/2P = $00A5, $00A5, $00A7, $00A7)
DSP4_READ_WORD();
DSP4_READ_WORD();
DSP4_READ_WORD();
DSP4_READ_WORD();
// polygon centering (left, right)
DSP4.poly_cx[0][0] = DSP4_READ_WORD();
DSP4.poly_cx[0][1] = DSP4_READ_WORD();
DSP4.poly_cx[1][0] = DSP4_READ_WORD();
DSP4.poly_cx[1][1] = DSP4_READ_WORD();
// HDMA pointer locations
DSP4.poly_ptr[0][0] = DSP4_READ_WORD();
DSP4.poly_ptr[0][1] = DSP4_READ_WORD();
DSP4.poly_ptr[1][0] = DSP4_READ_WORD();
DSP4.poly_ptr[1][1] = DSP4_READ_WORD();
// starting raster line below the horizon
DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
DSP4.poly_bottom[0][1] = DSP4_READ_WORD();
DSP4.poly_bottom[1][0] = DSP4_READ_WORD();
DSP4.poly_bottom[1][1] = DSP4_READ_WORD();
// top boundary line to clip
DSP4.poly_top[0][0] = DSP4_READ_WORD();
DSP4.poly_top[0][1] = DSP4_READ_WORD();
DSP4.poly_top[1][0] = DSP4_READ_WORD();
DSP4.poly_top[1][1] = DSP4_READ_WORD();
// unknown
// (ex. 1P = $2FC8, $0034, $FF5C, $0035)
//
// (ex. 2P = $3178, $0034, $FFCC, $0035)
// (ex. 2P = $2FC8, $0034, $FFCC, $0035)
DSP4_READ_WORD();
DSP4_READ_WORD();
DSP4_READ_WORD();
DSP4_READ_WORD();
// look at guidelines for both polygon shapes
DSP4.distance = DSP4_READ_WORD();
view_x[0] = DSP4_READ_WORD();
view_y[0] = DSP4_READ_WORD();
view_x[1] = DSP4_READ_WORD();
view_y[1] = DSP4_READ_WORD();
// envelope shaping guidelines (one frame only)
envelope[0][0] = DSP4_READ_WORD();
envelope[0][1] = DSP4_READ_WORD();
envelope[1][0] = DSP4_READ_WORD();
envelope[1][1] = DSP4_READ_WORD();
// starting base values to project from
DSP4.poly_start[0] = view_x[0];
DSP4.poly_start[1] = view_x[1];
// starting raster lines to begin drawing
DSP4.poly_raster[0][0] = view_y[0];
DSP4.poly_raster[0][1] = view_y[0];
DSP4.poly_raster[1][0] = view_y[1];
DSP4.poly_raster[1][1] = view_y[1];
// starting distances
DSP4.poly_plane[0] = DSP4.distance;
DSP4.poly_plane[1] = DSP4.distance;
// SR = 0x00
// re-center coordinates
win_left = DSP4.poly_cx[0][0] - view_x[0] + envelope[0][0];
win_right = DSP4.poly_cx[0][1] - view_x[0] + envelope[0][1];
// saturate offscreen data for polygon #1
if (win_left < DSP4.poly_clipLf[0][0])
win_left = DSP4.poly_clipLf[0][0];
if (win_left > DSP4.poly_clipRt[0][0])
win_left = DSP4.poly_clipRt[0][0];
if (win_right < DSP4.poly_clipLf[0][1])
win_right = DSP4.poly_clipLf[0][1];
if (win_right > DSP4.poly_clipRt[0][1])
win_right = DSP4.poly_clipRt[0][1];
// SR = 0x80
// initial output for polygon #1
DSP4_CLEAR_OUT();
DSP4_WRITE_BYTE(win_left & 0xff);
DSP4_WRITE_BYTE(win_right & 0xff);
do
{
int16 polygon;
////////////////////////////////////////////////////
// command check
// scan next command
DSP4.in_count = 2;
DSP4_WAIT(1);
resume1:
// terminate op
DSP4.distance = DSP4_READ_WORD();
if (DSP4.distance == -0x8000)
break;
// already have 2 bytes in queue
DSP4.in_count = 16;
DSP4_WAIT(2);
resume2:
// look at guidelines for both polygon shapes
view_x[0] = DSP4_READ_WORD();
view_y[0] = DSP4_READ_WORD();
view_x[1] = DSP4_READ_WORD();
view_y[1] = DSP4_READ_WORD();
// envelope shaping guidelines (one frame only)
envelope[0][0] = DSP4_READ_WORD();
envelope[0][1] = DSP4_READ_WORD();
envelope[1][0] = DSP4_READ_WORD();
envelope[1][1] = DSP4_READ_WORD();
////////////////////////////////////////////////////
// projection begins
// init
DSP4_CLEAR_OUT();
//////////////////////////////////////////////
// solid polygon renderer - 2 shapes
for (polygon = 0; polygon < 2; polygon++)
{
int32 left_inc, right_inc;
int16 x1_final, x2_final;
int16 env[2][2];
int16 poly;
// SR = 0x00
// # raster lines to draw
DSP4.segments = DSP4.poly_raster[polygon][0] - view_y[polygon];
// prevent overdraw
if (DSP4.segments > 0)
{
// bump drawing cursor
DSP4.poly_raster[polygon][0] = view_y[polygon];
DSP4.poly_raster[polygon][1] = view_y[polygon];
}
else
DSP4.segments = 0;
// don't draw outside the window
if (view_y[polygon] < DSP4.poly_top[polygon][0])
{
DSP4.segments = 0;
// flush remaining raster lines
if (view_y[polygon] >= DSP4.poly_top[polygon][0])
DSP4.segments = view_y[polygon] - DSP4.poly_top[polygon][0];
}
// SR = 0x80
// tell user how many raster structures to read in
DSP4_WRITE_WORD(DSP4.segments);
// normal parameters
poly = polygon;
/////////////////////////////////////////////////////
// scan next command if no SR check needed
if (DSP4.segments)
{
int32 w_left, w_right;
// road turnoff selection
if ((uint16) envelope[polygon][0] == (uint16) 0xc001)
poly = 1;
else
if (envelope[polygon][1] == 0x3fff)
poly = 1;
///////////////////////////////////////////////
// left side of polygon
// perspective correction on additional shaping parameters
env[0][0] = envelope[polygon][0] * DSP4.poly_plane[poly] >> 15;
env[0][1] = envelope[polygon][0] * DSP4.distance >> 15;
// project new shapes (left side)
x1_final = view_x[poly] + env[0][0];
x2_final = DSP4.poly_start[poly] + env[0][1];
// interpolate between projected points with shaping
left_inc = (x2_final - x1_final) * DSP4_Inverse(DSP4.segments) << 1;
if (DSP4.segments == 1)
left_inc = -left_inc;
///////////////////////////////////////////////
// right side of polygon
// perspective correction on additional shaping parameters
env[1][0] = envelope[polygon][1] * DSP4.poly_plane[poly] >> 15;
env[1][1] = envelope[polygon][1] * DSP4.distance >> 15;
// project new shapes (right side)
x1_final = view_x[poly] + env[1][0];
x2_final = DSP4.poly_start[poly] + env[1][1];
// interpolate between projected points with shaping
right_inc = (x2_final - x1_final) * DSP4_Inverse(DSP4.segments) << 1;
if (DSP4.segments == 1)
right_inc = -right_inc;
///////////////////////////////////////////////
// update each point on the line
w_left = SEX16(DSP4.poly_cx[polygon][0] - DSP4.poly_start[poly] + env[0][0]);
w_right = SEX16(DSP4.poly_cx[polygon][1] - DSP4.poly_start[poly] + env[1][0]);
// update distance drawn into world
DSP4.poly_plane[polygon] = DSP4.distance;
// rasterize line
for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
{
int16 x_left, x_right;
// project new coordinates
w_left += left_inc;
w_right += right_inc;
// grab integer portion, drop fraction (no rounding)
x_left = w_left >> 16;
x_right = w_right >> 16;
// saturate offscreen data
if (x_left < DSP4.poly_clipLf[polygon][0])
x_left = DSP4.poly_clipLf[polygon][0];
if (x_left > DSP4.poly_clipRt[polygon][0])
x_left = DSP4.poly_clipRt[polygon][0];
if (x_right < DSP4.poly_clipLf[polygon][1])
x_right = DSP4.poly_clipLf[polygon][1];
if (x_right > DSP4.poly_clipRt[polygon][1])
x_right = DSP4.poly_clipRt[polygon][1];
// 1. HDMA memory pointer
// 2. Left window position ($2126/$2128)
// 3. Right window position ($2127/$2129)
DSP4_WRITE_WORD(DSP4.poly_ptr[polygon][0]);
DSP4_WRITE_BYTE(x_left & 0xff);
DSP4_WRITE_BYTE(x_right & 0xff);
// update memory pointers
DSP4.poly_ptr[polygon][0] -= 4;
DSP4.poly_ptr[polygon][1] -= 4;
} // end rasterize line
}
////////////////////////////////////////////////
// Post-update
// new projection spot to continue rasterizing from
DSP4.poly_start[polygon] = view_x[poly];
} // end polygon rasterizer
}
while (1);
// unknown output
DSP4_CLEAR_OUT();
DSP4_WRITE_WORD(0);
DSP4.waiting4command = TRUE;
}
static void DSP4_OP09 (void)
{
DSP4.waiting4command = FALSE;
// op flow control
switch (DSP4.Logic)
{
case 1: goto resume1; break;
case 2: goto resume2; break;
case 3: goto resume3; break;
case 4: goto resume4; break;
case 5: goto resume5; break;
case 6: goto resume6; break;
}
////////////////////////////////////////////////////
// process initial inputs
// grab screen information
DSP4.viewport_cx = DSP4_READ_WORD();
DSP4.viewport_cy = DSP4_READ_WORD();
DSP4_READ_WORD(); // 0x0000
DSP4.viewport_left = DSP4_READ_WORD();
DSP4.viewport_right = DSP4_READ_WORD();
DSP4.viewport_top = DSP4_READ_WORD();
DSP4.viewport_bottom = DSP4_READ_WORD();
// starting raster line below the horizon
DSP4.poly_bottom[0][0] = DSP4.viewport_bottom - DSP4.viewport_cy;
DSP4.poly_raster[0][0] = 0x100;
do
{
////////////////////////////////////////////////////
// check for new sprites
DSP4.in_count = 4;
DSP4_WAIT(1);
resume1:
////////////////////////////////////////////////
// raster overdraw check
DSP4.raster = DSP4_READ_WORD();
// continue updating the raster line where overdraw begins
if (DSP4.raster < DSP4.poly_raster[0][0])
{
DSP4.sprite_clipy = DSP4.viewport_bottom - (DSP4.poly_bottom[0][0] - DSP4.raster);
DSP4.poly_raster[0][0] = DSP4.raster;
}
/////////////////////////////////////////////////
// identify sprite
// op termination
DSP4.distance = DSP4_READ_WORD();
if (DSP4.distance == -0x8000)
goto terminate;
// no sprite
if (DSP4.distance == 0x0000)
continue;
////////////////////////////////////////////////////
// process projection information
// vehicle sprite
if ((uint16) DSP4.distance == 0x9000)
{
int16 car_left, car_right, car_back;
int16 impact_left, impact_back;
int16 world_spx, world_spy;
int16 view_spx, view_spy;
uint16 energy;
// we already have 4 bytes we want
DSP4.in_count = 14;
DSP4_WAIT(2);
resume2:
// filter inputs
energy = DSP4_READ_WORD();
impact_back = DSP4_READ_WORD();
car_back = DSP4_READ_WORD();
impact_left = DSP4_READ_WORD();
car_left = DSP4_READ_WORD();
DSP4.distance = DSP4_READ_WORD();
car_right = DSP4_READ_WORD();
// calculate car's world (x, y) values
world_spx = car_right - car_left;
world_spy = car_back;
// add in collision vector [needs bit-twiddling]
world_spx -= energy * (impact_left - car_left) >> 16;
world_spy -= energy * (car_back - impact_back) >> 16;
// perspective correction for world (x, y)
view_spx = world_spx * DSP4.distance >> 15;
view_spy = world_spy * DSP4.distance >> 15;
// convert to screen values
DSP4.sprite_x = DSP4.viewport_cx + view_spx;
DSP4.sprite_y = DSP4.viewport_bottom - (DSP4.poly_bottom[0][0] - view_spy);
// make the car's (x)-coordinate available
DSP4_CLEAR_OUT();
DSP4_WRITE_WORD(world_spx);
// grab a few remaining vehicle values
DSP4.in_count = 4;
DSP4_WAIT(3);
resume3:
// add vertical lift factor
DSP4.sprite_y += DSP4_READ_WORD();
}
// terrain sprite
else
{
int16 world_spx, world_spy;
int16 view_spx, view_spy;
// we already have 4 bytes we want
DSP4.in_count = 10;
DSP4_WAIT(4);
resume4:
// sort loop inputs
DSP4.poly_cx[0][0] = DSP4_READ_WORD();
DSP4.poly_raster[0][1] = DSP4_READ_WORD();
world_spx = DSP4_READ_WORD();
world_spy = DSP4_READ_WORD();
// compute base raster line from the bottom
DSP4.segments = DSP4.poly_bottom[0][0] - DSP4.raster;
// perspective correction for world (x, y)
view_spx = world_spx * DSP4.distance >> 15;
view_spy = world_spy * DSP4.distance >> 15;
// convert to screen values
DSP4.sprite_x = DSP4.viewport_cx + view_spx - DSP4.poly_cx[0][0];
DSP4.sprite_y = DSP4.viewport_bottom - DSP4.segments + view_spy;
}
// default sprite size: 16x16
DSP4.sprite_size = 1;
DSP4.sprite_attr = DSP4_READ_WORD();
////////////////////////////////////////////////////
// convert tile data to SNES OAM format
do
{
int16 sp_x, sp_y, sp_attr, sp_dattr;
int16 sp_dx, sp_dy;
int16 pixels;
uint16 header;
bool8 draw;
DSP4.in_count = 2;
DSP4_WAIT(5);