auto import from //depot/cupcake/@135843

1 files changed, 0 insertions, 1173 deletions

diff --git a/libpixelflinger/trap.cpp b/libpixelflinger/trap.cpp
deleted file mode 100644
index 30b633f1..00000000
--- a/libpixelflinger/trap.cpp
+++ /dev/null
@@ -1,1173 +0,0 @@
-/* libs/pixelflinger/trap.cpp
-**
-** Copyright 2006, The Android Open Source Project
-**
-** Licensed under the Apache License, Version 2.0 (the "License"); 
-** you may not use this file except in compliance with the License. 
-** You may obtain a copy of the License at 
-**
-**     http://www.apache.org/licenses/LICENSE-2.0 
-**
-** Unless required by applicable law or agreed to in writing, software 
-** distributed under the License is distributed on an "AS IS" BASIS, 
-** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
-** See the License for the specific language governing permissions and 
-** limitations under the License.
-*/
-
-#include <assert.h>
-#include <stdio.h>
-#include <stdlib.h>
-
-#include "trap.h"
-#include "picker.h"
-
-#include <cutils/log.h>
-#include <cutils/memory.h>
-
-namespace android {
-
-// ----------------------------------------------------------------------------
-
-// enable to see triangles edges
-#define DEBUG_TRANGLES  0
-
-// ----------------------------------------------------------------------------
-
-static void pointx_validate(void *con, const GGLcoord* c, GGLcoord r);
-static void pointx(void *con, const GGLcoord* c, GGLcoord r);
-static void aa_pointx(void *con, const GGLcoord* c, GGLcoord r);
-static void aa_nice_pointx(void *con, const GGLcoord* c, GGLcoord r);
-
-static void linex_validate(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
-static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
-static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w);
-
-static void recti_validate(void* c, GGLint l, GGLint t, GGLint r, GGLint b); 
-static void recti(void* c, GGLint l, GGLint t, GGLint r, GGLint b); 
-
-static void trianglex_validate(void*,
-        const GGLcoord*, const GGLcoord*, const GGLcoord*);
-static void trianglex_small(void*,
-        const GGLcoord*, const GGLcoord*, const GGLcoord*);
-static void trianglex_big(void*,
-        const GGLcoord*, const GGLcoord*, const GGLcoord*);
-static void aa_trianglex(void*,
-        const GGLcoord*, const GGLcoord*, const GGLcoord*);
-static void trianglex_debug(void* con,
-        const GGLcoord*, const GGLcoord*, const GGLcoord*);
-
-static void aapolyx(void* con,
-        const GGLcoord* pts, int count);
-
-static inline int min(int a, int b) CONST;
-static inline int max(int a, int b) CONST;
-static inline int min(int a, int b, int c) CONST;
-static inline int max(int a, int b, int c) CONST;
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Tools
-#endif
-
-inline int min(int a, int b) {
-    return a<b ? a : b;
-}
-inline int max(int a, int b) {
-    return a<b ? b : a;
-}
-inline int min(int a, int b, int c) {
-    return min(a,min(b,c));
-}
-inline int max(int a, int b, int c) {
-    return max(a,max(b,c));
-}
-
-template <typename T>
-static inline void swap(T& a, T& b) {
-    T t(a);
-    a = b;
-    b = t;
-}
-
-static void
-triangle_dump_points( const GGLcoord*  v0,
-                      const GGLcoord*  v1,
-				 	  const GGLcoord*  v2 )
-{
-    float tri = 1.0f / TRI_ONE;
-  LOGD(     "  P0=(%.3f, %.3f)  [%08x, %08x]\n"
-            "  P1=(%.3f, %.3f)  [%08x, %08x]\n"
-            "  P2=(%.3f, %.3f)  [%08x, %08x]\n",
-		v0[0]*tri, v0[1]*tri, v0[0], v0[1],
-		v1[0]*tri, v1[1]*tri, v1[0], v1[1],
-		v2[0]*tri, v2[1]*tri, v2[0], v2[1] );
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Misc
-#endif
-
-void ggl_init_trap(context_t* c)
-{
-    ggl_state_changed(c, GGL_PIXEL_PIPELINE_STATE|GGL_TMU_STATE|GGL_CB_STATE);
-}
-
-void ggl_state_changed(context_t* c, int flags)
-{
-    if (ggl_likely(!c->dirty)) {
-        c->procs.pointx     = pointx_validate;
-        c->procs.linex      = linex_validate;
-        c->procs.recti      = recti_validate;
-        c->procs.trianglex  = trianglex_validate;
-    }
-    c->dirty |= uint32_t(flags);
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Point
-#endif
-
-void pointx_validate(void *con, const GGLcoord* v, GGLcoord rad)
-{
-    GGL_CONTEXT(c, con);
-    ggl_pick(c);
-    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
-        if (c->state.enables & GGL_ENABLE_POINT_AA_NICE) {
-            c->procs.pointx = aa_nice_pointx;
-        } else {
-            c->procs.pointx = aa_pointx;
-        }
-    } else {
-        c->procs.pointx = pointx;
-    }
-    c->procs.pointx(con, v, rad);
-}
-
-void pointx(void *con, const GGLcoord* v, GGLcoord rad)
-{
-    GGL_CONTEXT(c, con);
-    GGLcoord halfSize = TRI_ROUND(rad) >> 1;
-    if (halfSize == 0)
-        halfSize = TRI_HALF;
-    GGLcoord xc = v[0]; 
-    GGLcoord yc = v[1];
-    if (halfSize & TRI_HALF) { // size odd
-        xc = TRI_FLOOR(xc) + TRI_HALF;
-        yc = TRI_FLOOR(yc) + TRI_HALF;
-    } else { // size even
-        xc = TRI_ROUND(xc);
-        yc = TRI_ROUND(yc);
-    }
-    GGLint l = (xc - halfSize) >> TRI_FRACTION_BITS;
-    GGLint t = (yc - halfSize) >> TRI_FRACTION_BITS;
-    GGLint r = (xc + halfSize) >> TRI_FRACTION_BITS;
-    GGLint b = (yc + halfSize) >> TRI_FRACTION_BITS;
-    recti(c, l, t, r, b);
-}
-
-// This way of computing the coverage factor, is more accurate and gives
-// better results for small circles, but it is also a lot slower.
-// Here we use super-sampling.
-static int32_t coverageNice(GGLcoord x, GGLcoord y, 
-        GGLcoord rmin, GGLcoord rmax, GGLcoord rr)
-{
-    const GGLcoord d2 = x*x + y*y;
-    if (d2 >= rmax) return 0;
-    if (d2 < rmin)  return 0x7FFF;
-
-    const int kSamples              =  4;
-    const int kInc                  =  4;    // 1/4 = 0.25
-    const int kCoverageUnit         =  1;    // 1/(4^2) = 0.0625
-    const GGLcoord kCoordOffset     = -6;    // -0.375
-
-    int hits = 0;
-    int x_sample = x + kCoordOffset;
-    for (int i=0 ; i<kSamples ; i++, x_sample += kInc) {
-        const int xval = rr - (x_sample * x_sample);
-        int y_sample = y + kCoordOffset;
-        for (int j=0 ; j<kSamples ; j++, y_sample += kInc) {
-            if (xval - (y_sample * y_sample) > 0)
-                hits += kCoverageUnit;
-        }
-    }
-    return min(0x7FFF, hits << (15 - kSamples));
-}
-
-
-void aa_nice_pointx(void *con, const GGLcoord* v, GGLcoord size)
-{
-    GGL_CONTEXT(c, con);
-
-    GGLcoord rad = ((size + 1)>>1);
-    GGLint l = (v[0] - rad) >> TRI_FRACTION_BITS;
-    GGLint t = (v[1] - rad) >> TRI_FRACTION_BITS;
-    GGLint r = (v[0] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
-    GGLint b = (v[1] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
-    GGLcoord xstart = TRI_FROM_INT(l) - v[0] + TRI_HALF; 
-    GGLcoord ystart = TRI_FROM_INT(t) - v[1] + TRI_HALF; 
-
-    // scissor...
-    if (l < GGLint(c->state.scissor.left)) {
-        xstart += TRI_FROM_INT(c->state.scissor.left-l);
-        l = GGLint(c->state.scissor.left);
-    }
-    if (t < GGLint(c->state.scissor.top)) {
-        ystart += TRI_FROM_INT(c->state.scissor.top-t);
-        t = GGLint(c->state.scissor.top);
-    }
-    if (r > GGLint(c->state.scissor.right)) {
-        r = GGLint(c->state.scissor.right);
-    }
-    if (b > GGLint(c->state.scissor.bottom)) {
-        b = GGLint(c->state.scissor.bottom);
-    }
-
-    int xc = r - l;
-    int yc = b - t;
-    if (xc>0 && yc>0) {
-        int16_t* covPtr = c->state.buffers.coverage;
-        const int32_t sqr2Over2 = 0xC; // rounded up
-        GGLcoord rr = rad*rad;
-        GGLcoord rmin = (rad - sqr2Over2)*(rad - sqr2Over2);
-        GGLcoord rmax = (rad + sqr2Over2)*(rad + sqr2Over2);
-        GGLcoord y = ystart;
-        c->iterators.xl = l;
-        c->iterators.xr = r;
-        c->init_y(c, t);
-        do {
-            // compute coverage factors for each pixel
-            GGLcoord x = xstart;
-            for (int i=l ; i<r ; i++) {
-                covPtr[i] = coverageNice(x, y, rmin, rmax, rr);
-                x += TRI_ONE;
-            }
-            y += TRI_ONE;
-            c->scanline(c);
-            c->step_y(c);
-        } while (--yc);
-    }
-}
-
-// This is a cheap way of computing the coverage factor for a circle.
-// We just lerp between the circles of radii r-sqrt(2)/2 and r+sqrt(2)/2
-static inline int32_t coverageFast(GGLcoord x, GGLcoord y,
-        GGLcoord rmin, GGLcoord rmax, GGLcoord scale)
-{
-    const GGLcoord d2 = x*x + y*y;
-    if (d2 >= rmax) return 0;
-    if (d2 < rmin)  return 0x7FFF;
-    return 0x7FFF - (d2-rmin)*scale;
-}
-
-void aa_pointx(void *con, const GGLcoord* v, GGLcoord size)
-{
-    GGL_CONTEXT(c, con);
-
-    GGLcoord rad = ((size + 1)>>1);
-    GGLint l = (v[0] - rad) >> TRI_FRACTION_BITS;
-    GGLint t = (v[1] - rad) >> TRI_FRACTION_BITS;
-    GGLint r = (v[0] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
-    GGLint b = (v[1] + rad + (TRI_ONE-1)) >> TRI_FRACTION_BITS;
-    GGLcoord xstart = TRI_FROM_INT(l) - v[0] + TRI_HALF; 
-    GGLcoord ystart = TRI_FROM_INT(t) - v[1] + TRI_HALF; 
-
-    // scissor...
-    if (l < GGLint(c->state.scissor.left)) {
-        xstart += TRI_FROM_INT(c->state.scissor.left-l);
-        l = GGLint(c->state.scissor.left);
-    }
-    if (t < GGLint(c->state.scissor.top)) {
-        ystart += TRI_FROM_INT(c->state.scissor.top-t);
-        t = GGLint(c->state.scissor.top);
-    }
-    if (r > GGLint(c->state.scissor.right)) {
-        r = GGLint(c->state.scissor.right);
-    }
-    if (b > GGLint(c->state.scissor.bottom)) {
-        b = GGLint(c->state.scissor.bottom);
-    }
-
-    int xc = r - l;
-    int yc = b - t;
-    if (xc>0 && yc>0) {
-        int16_t* covPtr = c->state.buffers.coverage;
-        rad <<= 4;
-        const int32_t sqr2Over2 = 0xB5;    // fixed-point 24.8
-        GGLcoord rmin = rad - sqr2Over2;
-        GGLcoord rmax = rad + sqr2Over2;
-        GGLcoord scale;
-        rmin *= rmin;
-        rmax *= rmax;
-        scale = 0x800000 / (rmax - rmin);
-        rmin >>= 8;
-        rmax >>= 8;
-
-        GGLcoord y = ystart;
-        c->iterators.xl = l;
-        c->iterators.xr = r;
-        c->init_y(c, t);
-
-        do {
-            // compute coverage factors for each pixel
-            GGLcoord x = xstart;
-            for (int i=l ; i<r ; i++) {
-                covPtr[i] = coverageFast(x, y, rmin, rmax, scale);
-                x += TRI_ONE;
-            }
-            y += TRI_ONE;
-            c->scanline(c);
-            c->step_y(c);
-        } while (--yc);
-    }
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Line
-#endif
-
-void linex_validate(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord w)
-{
-    GGL_CONTEXT(c, con);
-    ggl_pick(c);
-    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
-        c->procs.linex = aa_linex;
-    } else {
-        c->procs.linex = linex;
-    }
-    c->procs.linex(con, v0, v1, w);
-}
-
-static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
-{
-    GGL_CONTEXT(c, con);
-    GGLcoord v[4][2];
-    v[0][0] = v0[0];    v[0][1] = v0[1];
-    v[1][0] = v1[0];    v[1][1] = v1[1];
-    v0 = v[0];
-    v1 = v[1];
-    const GGLcoord dx = abs(v0[0] - v1[0]);
-    const GGLcoord dy = abs(v0[1] - v1[1]);
-    GGLcoord nx, ny;
-    nx = ny = 0;
-
-    GGLcoord halfWidth = TRI_ROUND(width) >> 1;
-    if (halfWidth == 0)
-        halfWidth = TRI_HALF;
-
-    ((dx > dy) ? ny : nx) = halfWidth;
-    v[2][0] = v1[0];    v[2][1] = v1[1];
-    v[3][0] = v0[0];    v[3][1] = v0[1];
-    v[0][0] += nx;      v[0][1] += ny;
-    v[1][0] += nx;      v[1][1] += ny;
-    v[2][0] -= nx;      v[2][1] -= ny;
-    v[3][0] -= nx;      v[3][1] -= ny;
-    trianglex_big(con, v[0], v[1], v[2]);
-    trianglex_big(con, v[0], v[2], v[3]);
-}
-
-static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
-{
-    GGL_CONTEXT(c, con);
-    GGLcoord v[4][2];
-    v[0][0] = v0[0];    v[0][1] = v0[1];
-    v[1][0] = v1[0];    v[1][1] = v1[1];
-    v0 = v[0];
-    v1 = v[1];
-    
-    const GGLcoord dx = v0[0] - v1[0];
-    const GGLcoord dy = v0[1] - v1[1];
-    GGLcoord nx = -dy;
-    GGLcoord ny =  dx;
-
-    // generally, this will be well below 1.0
-    const GGLfixed norm = gglMulx(width, gglSqrtRecipx(nx*nx+ny*ny), 4);
-    nx = gglMulx(nx, norm, 21);
-    ny = gglMulx(ny, norm, 21);
-    
-    v[2][0] = v1[0];    v[2][1] = v1[1];
-    v[3][0] = v0[0];    v[3][1] = v0[1];
-    v[0][0] += nx;      v[0][1] += ny;
-    v[1][0] += nx;      v[1][1] += ny;
-    v[2][0] -= nx;      v[2][1] -= ny;
-    v[3][0] -= nx;      v[3][1] -= ny;
-    aapolyx(con, v[0], 4);        
-}
-
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Rect
-#endif
-
-void recti_validate(void *con, GGLint l, GGLint t, GGLint r, GGLint b)
-{
-    GGL_CONTEXT(c, con);
-    ggl_pick(c);
-    c->procs.recti = recti;
-    c->procs.recti(con, l, t, r, b);
-}
-
-void recti(void* con, GGLint l, GGLint t, GGLint r, GGLint b)
-{
-    GGL_CONTEXT(c, con);
-
-    // scissor...
-    if (l < GGLint(c->state.scissor.left))
-        l = GGLint(c->state.scissor.left);
-    if (t < GGLint(c->state.scissor.top))
-        t = GGLint(c->state.scissor.top);
-    if (r > GGLint(c->state.scissor.right))
-        r = GGLint(c->state.scissor.right);
-    if (b > GGLint(c->state.scissor.bottom))
-        b = GGLint(c->state.scissor.bottom);
-
-    int xc = r - l;
-    int yc = b - t;
-    if (xc>0 && yc>0) {
-        c->iterators.xl = l;
-        c->iterators.xr = r;
-        c->init_y(c, t);
-        c->rect(c, yc);
-    }
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Triangle / Debugging
-#endif
-
-static void scanline_set(context_t* c)
-{
-    int32_t x = c->iterators.xl;
-    size_t ct = c->iterators.xr - x;
-    int32_t y = c->iterators.y;
-    surface_t* cb = &(c->state.buffers.color);
-    const GGLFormat* fp = &(c->formats[cb->format]);
-    uint8_t* dst = reinterpret_cast<uint8_t*>(cb->data) +
-                            (x + (cb->stride * y)) * fp->size;
-    const size_t size = ct * fp->size;
-    memset(dst, 0xFF, size);
-}
-
-static void trianglex_debug(void* con,
-        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
-{
-    GGL_CONTEXT(c, con);
-    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
-        aa_trianglex(con,v0,v1,v2);
-    } else {
-        trianglex_big(con,v0,v1,v2);
-    }
-	void (*save_scanline)(context_t*)  = c->scanline;
-    c->scanline = scanline_set;
-    linex(con, v0, v1, TRI_ONE);
-    linex(con, v1, v2, TRI_ONE);
-    linex(con, v2, v0, TRI_ONE);
-    c->scanline = save_scanline;
-}
-
-static void trianglex_xor(void* con,
-        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
-{
-    trianglex_big(con,v0,v1,v2);
-    trianglex_small(con,v0,v1,v2);
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#pragma mark Triangle
-#endif
-
-void trianglex_validate(void *con,
-        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
-{
-    GGL_CONTEXT(c, con);
-    ggl_pick(c);
-    if (c->state.needs.p & GGL_NEED_MASK(P_AA)) {
-        c->procs.trianglex = DEBUG_TRANGLES ? trianglex_debug : aa_trianglex;
-    } else {
-        c->procs.trianglex = DEBUG_TRANGLES ? trianglex_debug : trianglex_big;
-    }
-    c->procs.trianglex(con, v0, v1, v2);
-}
-
-// ----------------------------------------------------------------------------
-
-void trianglex_small(void* con,
-        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
-{
-    GGL_CONTEXT(c, con);
-
-    // vertices are in 28.4 fixed point, which allows
-    // us to use 32 bits multiplies below.
-    int32_t x0 = v0[0];
-    int32_t y0 = v0[1];
-    int32_t x1 = v1[0];
-    int32_t y1 = v1[1];
-    int32_t x2 = v2[0];
-    int32_t y2 = v2[1];
-
-    int32_t dx01 = x0 - x1;
-    int32_t dy20 = y2 - y0;
-    int32_t dy01 = y0 - y1;
-    int32_t dx20 = x2 - x0;
-
-    // The code below works only with CCW triangles
-    // so if we get a CW triangle, we need to swap two of its vertices
-    if (dx01*dy20 < dy01*dx20) {
-        swap(x0, x1);
-        swap(y0, y1);
-        dx01 = x0 - x1;
-        dy01 = y0 - y1;
-        dx20 = x2 - x0;
-        dy20 = y2 - y0;
-    }
-    int32_t dx12 = x1 - x2;
-    int32_t dy12 = y1 - y2;
-
-    // bounding box & scissor
-    const int32_t bminx = TRI_FLOOR(min(x0, x1, x2)) >> TRI_FRACTION_BITS;
-    const int32_t bminy = TRI_FLOOR(min(y0, y1, y2)) >> TRI_FRACTION_BITS;
-    const int32_t bmaxx = TRI_CEIL( max(x0, x1, x2)) >> TRI_FRACTION_BITS;
-    const int32_t bmaxy = TRI_CEIL( max(y0, y1, y2)) >> TRI_FRACTION_BITS;
-    const int32_t minx = max(bminx, c->state.scissor.left);
-    const int32_t miny = max(bminy, c->state.scissor.top);
-    const int32_t maxx = min(bmaxx, c->state.scissor.right);
-    const int32_t maxy = min(bmaxy, c->state.scissor.bottom);
-    if ((minx >= maxx) || (miny >= maxy))
-        return; // too small or clipped out...
-
-    // step equations to the bounding box and snap to pixel center
-    const int32_t my = (miny << TRI_FRACTION_BITS) + TRI_HALF;
-    const int32_t mx = (minx << TRI_FRACTION_BITS) + TRI_HALF;
-    int32_t ey0 = dy01 * (x0 - mx) - dx01 * (y0 - my);
-    int32_t ey1 = dy12 * (x1 - mx) - dx12 * (y1 - my);
-    int32_t ey2 = dy20 * (x2 - mx) - dx20 * (y2 - my);
-
-    // right-exclusive fill rule, to avoid rare cases
-    // of over drawing
-    if (dy01<0 || (dy01 == 0 && dx01>0)) ey0++;
-    if (dy12<0 || (dy12 == 0 && dx12>0)) ey1++;
-    if (dy20<0 || (dy20 == 0 && dx20>0)) ey2++;
-    
-    c->init_y(c, miny);
-    for (int32_t y = miny; y < maxy; y++) {
-        register int32_t ex0 = ey0;
-        register int32_t ex1 = ey1;
-        register int32_t ex2 = ey2;    
-        register int32_t xl, xr;
-        for (xl=minx ; xl<maxx ; xl++) {
-            if (ex0>0 && ex1>0 && ex2>0)
-                break; // all strictly positive
-            ex0 -= dy01 << TRI_FRACTION_BITS;
-            ex1 -= dy12 << TRI_FRACTION_BITS;
-            ex2 -= dy20 << TRI_FRACTION_BITS;
-        }
-        xr = xl;
-        for ( ; xr<maxx ; xr++) {
-            if (!(ex0>0 && ex1>0 && ex2>0))
-                break; // not all strictly positive
-            ex0 -= dy01 << TRI_FRACTION_BITS;
-            ex1 -= dy12 << TRI_FRACTION_BITS;
-            ex2 -= dy20 << TRI_FRACTION_BITS;
-        }
-
-        if (xl < xr) {
-            c->iterators.xl = xl;
-            c->iterators.xr = xr;
-            c->scanline(c);
-        }
-        c->step_y(c);
-
-        ey0 += dx01 << TRI_FRACTION_BITS;
-        ey1 += dx12 << TRI_FRACTION_BITS;
-        ey2 += dx20 << TRI_FRACTION_BITS;
-    }
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#endif
-
-// the following routine fills a triangle via edge stepping, which
-// unfortunately requires divisions in the setup phase to get right,
-// it should probably only be used for relatively large trianges
-
-
-// x = y*DX/DY    (ou DX and DY are constants, DY > 0, et y >= 0)
-// 
-// for an equation of the type:
-//      x' = y*K/2^p     (with K and p constants "carefully chosen")
-// 
-// We can now do a DDA without precision loss. We define 'e' by:
-//      x' - x = y*(DX/DY - K/2^p) = y*e
-// 
-// If we choose K = round(DX*2^p/DY) then,
-//      abs(e) <= 1/2^(p+1) by construction
-// 
-// therefore abs(x'-x) = y*abs(e) <= y/2^(p+1) <= DY/2^(p+1) <= DMAX/2^(p+1)
-// 
-// which means that if DMAX <= 2^p, therefore abs(x-x') <= 1/2, including
-// at the last line. In fact, it's even a strict inequality except in one
-// extrem case (DY == DMAX et e = +/- 1/2)
-// 
-// Applying that to our coordinates, we need 2^p >= 4096*16 = 65536
-// so p = 16 is enough, we're so lucky!
-
-const int TRI_ITERATORS_BITS = 16;
-
-struct Edge
-{
-  int32_t  x;      // edge position in 16.16 coordinates
-  int32_t  x_incr; // on each step, increment x by that amount
-  int32_t  y_top;  // starting scanline, 16.4 format
-  int32_t  y_bot;
-};
-
-static void
-edge_dump( Edge*  edge )
-{
-  LOGI( "  top=%d (%.3f)  bot=%d (%.3f)  x=%d (%.3f)  ix=%d (%.3f)",
-        edge->y_top, edge->y_top/float(TRI_ONE),
-		edge->y_bot, edge->y_bot/float(TRI_ONE),
-		edge->x, edge->x/float(FIXED_ONE),
-		edge->x_incr, edge->x_incr/float(FIXED_ONE) );
-}
-
-static void
-triangle_dump_edges( Edge*  edges,
-                     int            count )
-{ 
-    LOGI( "%d edge%s:\n", count, count == 1 ? "" : "s" );
-	for ( ; count > 0; count--, edges++ )
-	  edge_dump( edges );
-}
-
-// the following function sets up an edge, it assumes
-// that ymin and ymax are in already in the 'reduced'
-// format
-static __attribute__((noinline))
-void edge_setup(
-        Edge*           edges,
-        int*            pcount,
-        const GGLcoord* p1,
-        const GGLcoord* p2,
-        int32_t         ymin,
-        int32_t         ymax )
-{
-	const GGLfixed*  top = p1;
-	const GGLfixed*  bot = p2;
-	Edge*    edge = edges + *pcount;
-
-	if (top[1] > bot[1]) {
-        swap(top, bot);
-	}
-
-	int  y1 = top[1] | 1;
-	int  y2 = bot[1] | 1;
-	int  dy = y2 - y1;
-
-	if ( dy == 0 || y1 > ymax || y2 < ymin )
-		return;
-
-	if ( y1 > ymin )
-		ymin = TRI_SNAP_NEXT_HALF(y1);
-	
-	if ( y2 < ymax )
-		ymax = TRI_SNAP_PREV_HALF(y2);
-
-	if ( ymin > ymax )  // when the edge doesn't cross any scanline
-	  return;
-
-	const int x1 = top[0];
-	const int dx = bot[0] - x1;
-    const int shift = TRI_ITERATORS_BITS - TRI_FRACTION_BITS;
-
-	// setup edge fields
-    // We add 0.5 to edge->x here because it simplifies the rounding
-    // in triangle_sweep_edges() -- this doesn't change the ordering of 'x'
-	edge->x      = (x1 << shift) + (1LU << (TRI_ITERATORS_BITS-1));
-	edge->x_incr = 0;
-	edge->y_top  = ymin;
-	edge->y_bot  = ymax;
-
-	if (ggl_likely(ymin <= ymax && dx)) {
-        edge->x_incr = gglDivQ16(dx, dy);
-    }
-    if (ggl_likely(y1 < ymin)) {
-        int32_t xadjust = (edge->x_incr * (ymin-y1)) >> TRI_FRACTION_BITS;
-        edge->x += xadjust;
-    }
-  
-	++*pcount;
-}
-
-
-static void
-triangle_sweep_edges( Edge*  left,
-                      Edge*  right,
-					  int            ytop,
-					  int            ybot,
-					  context_t*     c )
-{
-    int count = ((ybot - ytop)>>TRI_FRACTION_BITS) + 1;
-    if (count<=0) return;
-
-    // sort the edges horizontally
-    if ((left->x > right->x) || 
-        ((left->x == right->x) && (left->x_incr > right->x_incr))) {
-        swap(left, right);
-    }
-
-    int left_x = left->x;
-    int right_x = right->x;
-    const int left_xi = left->x_incr;
-    const int right_xi  = right->x_incr;
-    left->x  += left_xi * count;
-    right->x += right_xi * count;
-
-	const int xmin = c->state.scissor.left;
-	const int xmax = c->state.scissor.right;
-    do {
-        // horizontal scissoring
-        const int32_t xl = max(left_x  >> TRI_ITERATORS_BITS, xmin);
-        const int32_t xr = min(right_x >> TRI_ITERATORS_BITS, xmax);
-        left_x  += left_xi;
-        right_x += right_xi;
-        // invoke the scanline rasterizer
-        if (ggl_likely(xl < xr)) {
-            c->iterators.xl = xl;
-            c->iterators.xr = xr;
-            c->scanline(c);
-        }
-		c->step_y(c);
-	} while (--count);
-}
-
-
-void trianglex_big(void* con,
-        const GGLcoord* v0, const GGLcoord* v1, const GGLcoord* v2)
-{
-    GGL_CONTEXT(c, con);
-
-    Edge edges[3];
-	int num_edges = 0;
-	int32_t ymin = TRI_FROM_INT(c->state.scissor.top)    + TRI_HALF;
-	int32_t ymax = TRI_FROM_INT(c->state.scissor.bottom) - TRI_HALF;
-	    
-	edge_setup( edges, &num_edges, v0, v1, ymin, ymax );
-	edge_setup( edges, &num_edges, v0, v2, ymin, ymax );
-	edge_setup( edges, &num_edges, v1, v2, ymin, ymax );
-
-    if (ggl_unlikely(num_edges<2))  // for really tiny triangles that don't
-		return;                     // cross any scanline centers
-
-    Edge* left  = &edges[0];
-    Edge* right = &edges[1];
-    Edge* other = &edges[2];
-    int32_t y_top = min(left->y_top, right->y_top);
-    int32_t y_bot = max(left->y_bot, right->y_bot);
-
-	if (ggl_likely(num_edges==3)) {
-        y_top = min(y_top, edges[2].y_top);
-        y_bot = max(y_bot, edges[2].y_bot);
-		if (edges[0].y_top > y_top) {
-            other = &edges[0];
-            left  = &edges[2];
-		} else if (edges[1].y_top > y_top) {
-            other = &edges[1];
-            right = &edges[2];
-		}
-    }
-
-    c->init_y(c, y_top >> TRI_FRACTION_BITS);
-
-    int32_t y_mid = min(left->y_bot, right->y_bot);
-    triangle_sweep_edges( left, right, y_top, y_mid, c );
-
-    // second scanline sweep loop, if necessary
-    y_mid += TRI_ONE;
-    if (y_mid <= y_bot) {
-        ((left->y_bot == y_bot) ? right : left) = other;
-        if (other->y_top < y_mid) {
-            other->x += other->x_incr;
-        }
-        triangle_sweep_edges( left, right, y_mid, y_bot, c );
-    }
-}
-
-void aa_trianglex(void* con,
-        const GGLcoord* a, const GGLcoord* b, const GGLcoord* c)
-{
-    GGLcoord pts[6] = { a[0], a[1], b[0], b[1], c[0], c[1] };
-    aapolyx(con, pts, 3);
-}
-
-// ----------------------------------------------------------------------------
-#if 0
-#pragma mark -
-#endif
-
-struct AAEdge
-{
-    GGLfixed x;         // edge position in 12.16 coordinates
-    GGLfixed x_incr;    // on each y step, increment x by that amount
-    GGLfixed y_incr;    // on each x step, increment y by that amount
-    int16_t y_top;      // starting scanline, 12.4 format
-    int16_t y_bot;      // starting scanline, 12.4 format
-    void dump();
-};
-
-void AAEdge::dump()
-{
-    float tri  = 1.0f / TRI_ONE;
-    float iter = 1.0f / (1<<TRI_ITERATORS_BITS);
-    float fix  = 1.0f / FIXED_ONE;
-    LOGD(   "x=%08x (%.3f), "
-            "x_incr=%08x (%.3f), y_incr=%08x (%.3f), "
-            "y_top=%08x (%.3f), y_bot=%08x (%.3f) ",
-        x, x*fix,
-        x_incr, x_incr*iter,
-        y_incr, y_incr*iter,
-        y_top, y_top*tri,
-        y_bot, y_bot*tri );
-}
-
-// the following function sets up an edge, it assumes
-// that ymin and ymax are in already in the 'reduced'
-// format
-static __attribute__((noinline))
-void aa_edge_setup(
-        AAEdge*         edges,
-        int*            pcount,
-        const GGLcoord* p1,
-        const GGLcoord* p2,
-        int32_t         ymin,
-        int32_t         ymax )
-{
-    const GGLfixed*  top = p1;
-    const GGLfixed*  bot = p2;
-    AAEdge* edge = edges + *pcount;
-
-    if (top[1] > bot[1])
-        swap(top, bot);
-
-    int  y1 = top[1];
-    int  y2 = bot[1];
-    int  dy = y2 - y1;
-
-    if (dy==0 || y1>ymax || y2<ymin)
-        return;
-
-    if (y1 > ymin)
-        ymin = y1;
-    
-    if (y2 < ymax)
-        ymax = y2;
-
-    const int x1 = top[0];
-    const int dx = bot[0] - x1;
-    const int shift = FIXED_BITS - TRI_FRACTION_BITS;
-
-    // setup edge fields
-    edge->x      = x1 << shift;
-    edge->x_incr = 0;
-    edge->y_top  = ymin;
-    edge->y_bot  = ymax;
-    edge->y_incr = 0x7FFFFFFF;
-
-    if (ggl_likely(ymin <= ymax && dx)) {
-        edge->x_incr = gglDivQ16(dx, dy);
-        if (dx != 0) {
-            edge->y_incr = abs(gglDivQ16(dy, dx));
-        }
-    }
-    if (ggl_likely(y1 < ymin)) {
-        int32_t xadjust = (edge->x_incr * (ymin-y1))
-                >> (TRI_FRACTION_BITS + TRI_ITERATORS_BITS - FIXED_BITS);
-        edge->x += xadjust;
-    }
-  
-    ++*pcount;
-}
-
-
-typedef int (*compar_t)(const void*, const void*);
-static int compare_edges(const AAEdge *e0, const AAEdge *e1) {
-    if (e0->y_top > e1->y_top)      return 1;
-    if (e0->y_top < e1->y_top)      return -1;
-    if (e0->x > e1->x)              return 1;
-    if (e0->x < e1->x)              return -1;
-    if (e0->x_incr > e1->x_incr)    return 1;
-    if (e0->x_incr < e1->x_incr)    return -1;
-    return 0; // same edges, should never happen
-}
-
-static inline 
-void SET_COVERAGE(int16_t*& p, int32_t value, ssize_t n)
-{
-    android_memset16((uint16_t*)p, value, n*2);
-    p += n;
-}
-
-static inline 
-void ADD_COVERAGE(int16_t*& p, int32_t value)
-{
-    value = *p + value;
-    if (value >= 0x8000)
-        value = 0x7FFF;
-    *p++ = value;
-}
-
-static inline
-void SUB_COVERAGE(int16_t*& p, int32_t value)
-{
-    value = *p - value;
-    value &= ~(value>>31);
-    *p++ = value;
-}
-
-void aapolyx(void* con,
-        const GGLcoord* pts, int count)
-{
-    /*
-     * NOTE: This routine assumes that the polygon has been clipped to the
-     * viewport already, that is, no vertex lies outside of the framebuffer.
-     * If this happens, the code below won't corrupt memory but the 
-     * coverage values may not be correct.
-     */
-    
-    GGL_CONTEXT(c, con);
-
-    // we do only quads for now (it's used for thick lines)
-    if ((count>4) || (count<2)) return;
-
-    // take scissor into account
-    const int xmin = c->state.scissor.left;
-    const int xmax = c->state.scissor.right;
-    if (xmin >= xmax) return;
-
-    // generate edges from the vertices
-    int32_t ymin = TRI_FROM_INT(c->state.scissor.top);
-    int32_t ymax = TRI_FROM_INT(c->state.scissor.bottom);
-    if (ymin >= ymax) return;
-
-    AAEdge edges[4];
-    int num_edges = 0;
-    GGLcoord const * p = pts;
-    for (int i=0 ; i<count-1 ; i++, p+=2) {
-        aa_edge_setup(edges, &num_edges, p, p+2, ymin, ymax);
-    }
-    aa_edge_setup(edges, &num_edges, p, pts, ymin, ymax );
-    if (ggl_unlikely(num_edges<2))
-        return;
-
-    // sort the edge list top to bottom, left to right.
-    qsort(edges, num_edges, sizeof(AAEdge), (compar_t)compare_edges);
-
-    int16_t* const covPtr = c->state.buffers.coverage;
-    memset(covPtr+xmin, 0, (xmax-xmin)*sizeof(*covPtr));
-
-    // now, sweep all edges in order
-    // start with the 2 first edges. We know that they share their top
-    // vertex, by construction.
-    int i = 2;
-    AAEdge* left  = &edges[0];
-    AAEdge* right = &edges[1];
-    int32_t yt = left->y_top;
-    GGLfixed l = left->x;
-    GGLfixed r = right->x;
-    int retire = 0;
-    int16_t* coverage;
-
-    // at this point we can initialize the rasterizer    
-    c->init_y(c, yt>>TRI_FRACTION_BITS);
-    c->iterators.xl = xmax;
-    c->iterators.xr = xmin;
-
-    do {
-        int32_t y = min(min(left->y_bot, right->y_bot), TRI_FLOOR(yt + TRI_ONE));
-        const int32_t shift = TRI_FRACTION_BITS + TRI_ITERATORS_BITS - FIXED_BITS;
-        const int cf_shift = (1 + TRI_FRACTION_BITS*2 + TRI_ITERATORS_BITS - 15);
-
-        // compute xmin and xmax for the left edge
-        GGLfixed l_min = gglMulAddx(left->x_incr, y - left->y_top, left->x, shift);
-        GGLfixed l_max = l;
-        l = l_min;
-        if (l_min > l_max)
-            swap(l_min, l_max);
-
-        // compute xmin and xmax for the right edge
-        GGLfixed r_min = gglMulAddx(right->x_incr, y - right->y_top, right->x, shift);
-        GGLfixed r_max = r;
-        r = r_min;
-        if (r_min > r_max)
-            swap(r_min, r_max);
-
-        // make sure we're not touching coverage values outside of the
-        // framebuffer
-        l_min &= ~(l_min>>31);
-        r_min &= ~(r_min>>31);
-        l_max &= ~(l_max>>31);
-        r_max &= ~(r_max>>31);
-        if (gglFixedToIntFloor(l_min) >= xmax) l_min = gglIntToFixed(xmax)-1;
-        if (gglFixedToIntFloor(r_min) >= xmax) r_min = gglIntToFixed(xmax)-1;
-        if (gglFixedToIntCeil(l_max) >= xmax)  l_max = gglIntToFixed(xmax)-1;
-        if (gglFixedToIntCeil(r_max) >= xmax)  r_max = gglIntToFixed(xmax)-1;
-
-        // compute the integer versions of the above
-        const GGLfixed l_min_i = gglFloorx(l_min);
-        const GGLfixed l_max_i = gglCeilx (l_max);
-        const GGLfixed r_min_i = gglFloorx(r_min);
-        const GGLfixed r_max_i = gglCeilx (r_max);
-
-        // clip horizontally using the scissor
-        const int xml = max(xmin, gglFixedToIntFloor(l_min_i));
-        const int xmr = min(xmax, gglFixedToIntFloor(r_max_i));
-
-        // if we just stepped to a new scanline, render the previous one.
-        // and clear the coverage buffer
-        if (retire) {
-            if (c->iterators.xl < c->iterators.xr)
-                c->scanline(c);
-            c->step_y(c);
-            memset(covPtr+xmin, 0, (xmax-xmin)*sizeof(*covPtr));
-            c->iterators.xl = xml;
-            c->iterators.xr = xmr;
-        } else {
-            // update the horizontal range of this scanline
-            c->iterators.xl = min(c->iterators.xl, xml);
-            c->iterators.xr = max(c->iterators.xr, xmr);
-        }
-
-        coverage = covPtr + gglFixedToIntFloor(l_min_i);
-        if (l_min_i == gglFloorx(l_max)) {
-            
-            /*
-             *  fully traverse this pixel vertically
-             *       l_max
-             *  +-----/--+  yt
-             *  |    /   |  
-             *  |   /    |
-             *  |  /     |
-             *  +-/------+  y
-             *   l_min  (l_min_i + TRI_ONE)
-             */
-              
-            GGLfixed dx = l_max - l_min;
-            int32_t dy = y - yt;
-            int cf = gglMulx((dx >> 1) + (l_min_i + FIXED_ONE - l_max), dy,
-                FIXED_BITS + TRI_FRACTION_BITS - 15);
-            ADD_COVERAGE(coverage, cf);
-            // all pixels on the right have cf = 1.0
-        } else {
-            /*
-             *  spans several pixels in one scanline
-             *            l_max
-             *  +--------+--/-----+  yt
-             *  |        |/       |
-             *  |       /|        |
-             *  |     /  |        |
-             *  +---/----+--------+  y
-             *   l_min (l_min_i + TRI_ONE)
-             */
-
-            // handle the first pixel separately...
-            const int32_t y_incr = left->y_incr;
-            int32_t dx = TRI_FROM_FIXED(l_min_i - l_min) + TRI_ONE;
-            int32_t cf = (dx * dx * y_incr) >> cf_shift;
-            ADD_COVERAGE(coverage, cf);
-
-            // following pixels get covered by y_incr, but we need
-            // to fix-up the cf to account for previous partial pixel
-            dx = TRI_FROM_FIXED(l_min - l_min_i);
-            cf -= (dx * dx * y_incr) >> cf_shift;
-            for (int x = l_min_i+FIXED_ONE ; x < l_max_i-FIXED_ONE ; x += FIXED_ONE) {
-                cf += y_incr >> (TRI_ITERATORS_BITS-15);
-                ADD_COVERAGE(coverage, cf);
-            }
-            
-            // and the last pixel
-            dx = TRI_FROM_FIXED(l_max - l_max_i) - TRI_ONE;
-            cf += (dx * dx * y_incr) >> cf_shift;
-            ADD_COVERAGE(coverage, cf);
-        }
-        
-        // now, fill up all fully covered pixels
-        coverage = covPtr + gglFixedToIntFloor(l_max_i);
-        int cf = ((y - yt) << (15 - TRI_FRACTION_BITS));
-        if (ggl_likely(cf >= 0x8000)) {
-            SET_COVERAGE(coverage, 0x7FFF, ((r_max - l_max_i)>>FIXED_BITS)+1);
-        } else {
-            for (int x=l_max_i ; x<r_max ; x+=FIXED_ONE) {
-                ADD_COVERAGE(coverage, cf);
-            }
-        }
-        
-        // subtract the coverage of the right edge
-        coverage = covPtr + gglFixedToIntFloor(r_min_i); 
-        if (r_min_i == gglFloorx(r_max)) {
-            GGLfixed dx = r_max - r_min;
-            int32_t dy = y - yt;
-            int cf = gglMulx((dx >> 1) + (r_min_i + FIXED_ONE - r_max), dy,
-                FIXED_BITS + TRI_FRACTION_BITS - 15);
-            SUB_COVERAGE(coverage, cf);
-            // all pixels on the right have cf = 1.0
-        } else {
-            // handle the first pixel separately...
-            const int32_t y_incr = right->y_incr;
-            int32_t dx = TRI_FROM_FIXED(r_min_i - r_min) + TRI_ONE;
-            int32_t cf = (dx * dx * y_incr) >> cf_shift;
-            SUB_COVERAGE(coverage, cf);
-            
-            // following pixels get covered by y_incr, but we need
-            // to fix-up the cf to account for previous partial pixel
-            dx = TRI_FROM_FIXED(r_min - r_min_i);
-            cf -= (dx * dx * y_incr) >> cf_shift;
-            for (int x = r_min_i+FIXED_ONE ; x < r_max_i-FIXED_ONE ; x += FIXED_ONE) {
-                cf += y_incr >> (TRI_ITERATORS_BITS-15);
-                SUB_COVERAGE(coverage, cf);
-            }
-            
-            // and the last pixel
-            dx = TRI_FROM_FIXED(r_max - r_max_i) - TRI_ONE;
-            cf += (dx * dx * y_incr) >> cf_shift;
-            SUB_COVERAGE(coverage, cf);
-        }
-
-        // did we reach the end of an edge? if so, get a new one.
-        if (y == left->y_bot || y == right->y_bot) {
-            // bail out if we're done
-            if (i>=num_edges)
-                break;
-            if (y == left->y_bot)
-                left = &edges[i++];
-            if (y == right->y_bot)
-                right = &edges[i++];
-        }
-
-        // next scanline
-        yt = y;
-        
-        // did we just finish a scanline?        
-        retire = (y << (32-TRI_FRACTION_BITS)) == 0;
-    } while (true);
-
-    // render the last scanline
-    if (c->iterators.xl < c->iterators.xr)
-        c->scanline(c);
-}
-
-}; // namespace android