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diff -urN old/xv-3.10a/xvsmooth.c xv-3.10a/xvsmooth.c
--- old/xv-3.10a/xvsmooth.c Thu Dec 22 17:34:42 1994
+++ xv-3.10a/xvsmooth.c Sun Aug 17 14:07:58 1997
@@ -65,10 +65,13 @@
returns a dwide*dhigh 24bit image, or NULL on failure (malloc) */
/* rmap,gmap,bmap should be 'desired' colors */
+ /* DANGER: This code assumes that a right-shift on signed integers is
+ performed arithmetically, i.e. the sign bit is copied to the right. */
+
byte *pic24, *pp;
- int *cxtab, *pxtab;
- int y1Off, cyOff;
- int ex, ey, cx, cy, px, py, apx, apy, x1, y1;
+ int *pxtab;
+ int ex, ey, px, py, x0, x1, y0, y1;
+ int y0off, y1off;
int cA, cB, cC, cD;
int pA, pB, pC, pD;
int retval, bperpix;
@@ -98,69 +101,61 @@
else {
/* dwide >= swide && dhigh >= shigh */
- /* cx,cy = original pixel in pic824. px,py = relative position
- of pixel ex,ey inside of cx,cy as percentages +-50%, +-50%.
- 0,0 = middle of pixel */
-
- /* we can save a lot of time by precomputing cxtab[] and pxtab[], both
- dwide arrays of ints that contain values for the equations:
- cx = (ex * swide) / dwide;
- px = ((ex * swide * 100) / dwide) - (cx * 100) - 50; */
-
- cxtab = (int *) malloc(dwide * sizeof(int));
- if (!cxtab) { free(pic24); return NULL; }
+ /* px, py = location on original image, in units of 1/256 pixel
+ We can save time by precomputing all values of px. */
pxtab = (int *) malloc(dwide * sizeof(int));
- if (!pxtab) { free(pic24); free(cxtab); return NULL; }
-
- for (ex=0; ex<dwide; ex++) {
- cxtab[ex] = (ex * swide) / dwide;
- pxtab[ex] = (((ex * swide)* 100) / dwide)
- - (cxtab[ex] * 100) - 50;
- }
+ if (!pxtab) { free(pic24); return NULL; }
- for (ey=0; ey<dhigh; ey++) {
+ for (ex=0; ex < dwide; ex++)
+ pxtab[ex] = ((ex << 8) + 128) * swide / dwide - 128;
+
+ for (ey=0; ey < dhigh; ey++) {
byte *pptr, rA, gA, bA, rB, gB, bB, rC, gC, bC, rD, gD, bD;
ProgressMeter(0, (dhigh)-1, ey, "Smooth");
- cy = (ey * shigh) / dhigh;
- py = (((ey * shigh) * 100) / dhigh) - (cy * 100) - 50;
- if (py<0) { y1 = cy-1; if (y1<0) y1=0; }
- else { y1 = cy+1; if (y1>shigh-1) y1=shigh-1; }
+ py = ((ey << 8) + 128) * shigh / dhigh - 128;
+ y0 = py >> 8; /* Put integer part in y0 */
+ y1 = y0 + 1;
+ py &= 255; /* Keep fractional part in py */
+
+ if (y0 < 0) y0 = y1 = 0;
+ if (y1 >= shigh) y0 = y1 = shigh-1;
- cyOff = cy * swide * bperpix; /* current line */
- y1Off = y1 * swide * bperpix; /* up or down one line, depending */
+ y0off = y0 * swide * bperpix; /* current line */
+ y1off = y1 * swide * bperpix; /* one line down */
if ((ey&15) == 0) WaitCursor();
- for (ex=0; ex<dwide; ex++) {
- rA = rB = rC = rD = gA = gB = gC = gD = bA = bB = bC = bD = 0;
+ for (ex=0; ex < dwide; ex++) {
- cx = cxtab[ex];
px = pxtab[ex];
+ x0 = px >> 8; /* Put integer part in x0 */
+ x1 = x0 + 1;
+ px &= 255; /* Keep fractional part in px */
- if (px<0) { x1 = cx-1; if (x1<0) x1=0; }
- else { x1 = cx+1; if (x1>swide-1) x1=swide-1; }
+ if (x0 < 0) x0 = x1 = 0;
+ if (x1 >= swide) x0 = x1 = swide-1;
if (is24) {
- pptr = pic824 + y1Off + x1*bperpix; /* corner pixel */
+ pptr = pic824 + y0off + x0*bperpix; /* upper left pixel */
rA = *pptr++; gA = *pptr++; bA = *pptr++;
- pptr = pic824 + y1Off + cx*bperpix; /* up/down center pixel */
+ pptr = pic824 + y0off + x1*bperpix; /* upper right pixel */
rB = *pptr++; gB = *pptr++; bB = *pptr++;
- pptr = pic824 + cyOff + x1*bperpix; /* left/right center pixel */
+ pptr = pic824 + y1off + x0*bperpix; /* lower left pixel */
rC = *pptr++; gC = *pptr++; bC = *pptr++;
- pptr = pic824 + cyOff + cx*bperpix; /* center pixel */
+ pptr = pic824 + y1off + x1*bperpix; /* lower right pixel */
rD = *pptr++; gD = *pptr++; bD = *pptr++;
}
else { /* 8-bit picture */
- cA = pic824[y1Off + x1]; /* corner pixel */
- cB = pic824[y1Off + cx]; /* up/down center pixel */
- cC = pic824[cyOff + x1]; /* left/right center pixel */
- cD = pic824[cyOff + cx]; /* center pixel */
+ cA = pic824[y0off + x0]; /* upper left pixel */
+ cB = pic824[y0off + x1]; /* upper right pixel */
+ cC = pic824[y1off + x0]; /* lower left pixel */
+ cD = pic824[y1off + x1]; /* lower right pixel */
}
/* quick check */
@@ -170,38 +165,30 @@
}
else {
- /* compute weighting factors */
- apx = abs(px); apy = abs(py);
- pA = (apx * apy) / 100;
- pB = (apy * (100 - apx)) / 100;
- pC = (apx * (100 - apy)) / 100;
- pD = 100 - (pA + pB + pC);
+ pA = (256-px)*(256-py); /* compute weighting factors */
+ pB = px * (256-py); /* total weight is exactly 2^16 */
+ pC = (256-px) * py;
+ pD = px * py;
if (is24) {
- *pp++ = ((int) (pA * rA))/100 + ((int) (pB * rB))/100 +
- ((int) (pC * rC))/100 + ((int) (pD * rD))/100;
-
- *pp++ = ((int) (pA * gA))/100 + ((int) (pB * gB))/100 +
- ((int) (pC * gC))/100 + ((int) (pD * gD))/100;
-
- *pp++ = ((int) (pA * bA))/100 + ((int) (pB * bB))/100 +
- ((int) (pC * bC))/100 + ((int) (pD * bD))/100;
+ *pp++ = (pA * rA + pB * rB + pC * rC + pD * rD) + 32768 >> 16;
+ *pp++ = (pA * gA + pB * gB + pC * gC + pD * gD) + 32768 >> 16;
+ *pp++ = (pA * bA + pB * bB + pC * bC + pD * bD) + 32768 >> 16;
}
else { /* 8-bit pic */
- *pp++ = ((int) (pA * rmap[cA]))/100 + ((int)(pB * rmap[cB]))/100 +
- ((int) (pC * rmap[cC]))/100 + ((int)(pD * rmap[cD]))/100;
+ *pp++ = (pA * rmap[cA] + pB * rmap[cB] + pC * rmap[cC] +
+ pD * rmap[cD]) + 32768 >> 16;
- *pp++ = ((int) (pA * gmap[cA]))/100 + ((int)(pB * gmap[cB]))/100 +
- ((int) (pC * gmap[cC]))/100 + ((int)(pD * gmap[cD]))/100;
+ *pp++ = (pA * gmap[cA] + pB * gmap[cB] + pC * gmap[cC] +
+ pD * gmap[cD]) + 32768 >> 16;
- *pp++ = ((int)(pA * bmap[cA]))/100 + ((int)(pB * bmap[cB]))/100 +
- ((int)(pC * bmap[cC]))/100 + ((int)(pD * bmap[cD]))/100;
+ *pp++ = (pA * bmap[cA] + pB * bmap[cB] + pC * bmap[cC] +
+ pD * bmap[cD]) + 32768 >> 16;
}
}
}
}
- free(cxtab);
free(pxtab);
retval = 0; /* okay */
}
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