ref: 776056dcd095c48fa0006c4150b98ad77423c1e6
parent: 176569ca4d97b271f6e3697bdc5b6e50fb5ff30b
author: ppatience0 <[email protected]>
date: Sun Jul 21 06:56:11 EDT 2013
readtif, writetif: remove multiplication in inner loops of predict functions
--- a/sys/src/cmd/jpg/readtif.c
+++ b/sys/src/cmd/jpg/readtif.c
@@ -442,8 +442,8 @@
static Code *tabadd(Lzw *, Code *, Code *);
static int getcode(Lzw *);
static int wstr(uchar *, ulong, ulong *, Code *, long *);
-static int predict1(Tif *, uchar *, ulong);
-static int predict8(Tif *, uchar *, ulong);
+static void predict1(Tif *, uchar *);
+static void predict8(Tif *, uchar *);
static int lzwstrip(Lzw *, uchar *, ulong, ulong *, long);
static uchar *lzw(Tif *);
static uchar *packbits(Tif *);
@@ -1096,27 +1096,22 @@
return 0;
}
-static int
-predict1(Tif *t, uchar *data, ulong ndata)
+static void
+predict1(Tif *t, uchar *data)
{int bpl, pix, b[8], d, m, n, j;
- ulong i, x, y;
+ ulong x, y;
- bpl = bytesperline(Rect(0, 0, t->dx, t->dy), t->depth);
d = t->depth;
+ bpl = bytesperline(Rect(0, 0, t->dx, t->dy), d);
m = (1 << d) - 1;
n = 8 / d;
for(y = 0; y < t->dy; y++) {- for(x = 0; x < bpl; x++) {- i = y*bpl + x;
- if(i >= ndata) {- werrstr("pred4 overflow");- return -1;
- }
- pix = data[i];
+ for(x = 0; x < bpl; x++, data++) {+ pix = *data;
b[n-1] = (pix >> d*(n-1)) & m;
if(x > 0)
- b[n-1] += data[i-1] & m;
+ b[n-1] += *(data-1) & m;
for(j = n-2; j >= 0; j--) {b[j] = (pix >> d*j) & m;
b[j] += b[j+1];
@@ -1123,34 +1118,23 @@
}
for(j = pix = 0; j < n; j++)
pix |= (b[j] & m) << d*j;
- data[i] = pix;
+ *data = pix;
}
}
- return 0;
}
-static int
-predict8(Tif *t, uchar *data, ulong ndata)
+static void
+predict8(Tif *t, uchar *data)
{- char a, b;
- ulong i, j, s, x, y;
+ ulong j, s, x, y;
s = t->samples;
for(y = 0; y < t->dy; y++) {- for(x = 1; x < t->dx; x++) {- i = (y*t->dx + x) * s;
- if(i+s-1 >= ndata) {- werrstr("pred8 overflow");- return -1;
- }
- for(j = 0; j < s; i++, j++) {- a = (char)data[i];
- b = (char)data[i-s];
- data[i] = (uchar)(a + b);
- }
+ for(x = 1, data += s; x < t->dx; x++) {+ for(j = 0; j < s; j++, data++)
+ *data += *(data-s);
}
}
- return 0;
}
static int
@@ -1215,7 +1199,6 @@
uchar *data;
Lzw l;
Code *p, *q;
- int (*predict)(Tif *, uchar *, ulong);
size = ((t->dx*t->dy*t->depth + 7) / 8) * sizeof *data;
if((data = malloc(size)) == nil) {@@ -1259,13 +1242,9 @@
free(t->data);
if(data != nil && t->predictor == 2) {if(t->depth < 8)
- predict = predict1;
+ predict1(t, data);
else
- predict = predict8;
- if((*predict)(t, data, size) < 0) {- free(data);
- return nil;
- }
+ predict8(t, data);
}
return data;
}
--- a/sys/src/cmd/jpg/writetif.c
+++ b/sys/src/cmd/jpg/writetif.c
@@ -792,27 +792,27 @@
predict1(Tif *t)
{int pix, b[8], d, m, n, j;
- ulong i, x, y;
+ ulong x, y;
+ uchar *data, *p;
+ p = t->data;
d = *t->depth;
m = (1 << d) - 1;
n = 8 / d;
for(y = 0; y < t->dy; y++) {- for(x = t->bpl-1;; x--) {- i = y*t->bpl + x;
- pix = t->data[i];
+ data = p += t->bpl;
+ for(x = t->bpl; x > 0; x--) {+ pix = *--data;
for(j = 0; j < n; j++) {b[j] = (pix >> d*j) & m;
if(j > 0)
b[j-1] -= b[j];
}
- if(x > 0)
- b[n-1] -= t->data[i-1] & m;
+ if(x > 1)
+ b[n-1] -= *(data-1) & m;
for(j = pix = 0; j < n; j++)
pix |= (b[j] & m) << d*j;
- t->data[i] = pix;
- if(x == 0)
- break;
+ *data = pix;
}
}
}
@@ -820,14 +820,18 @@
static void
predict8(Tif *t)
{- ulong i, j, s, x, y;
+ ulong j, s, x, y;
+ uchar *data, *p;
+ p = t->data;
s = t->samples;
for(y = 0; y < t->dy; y++) {- for(x = t->dx-1; x >= 1; x--) {- i = (y*t->dx + x) * s;
- for(j = 0; j < s; i++, j++)
- t->data[i] -= t->data[i-s];
+ data = p += t->dx * s;
+ for(x = t->dx; x > 1; x--) {+ for(j = 0; j < s; j++) {+ data--;
+ *data -= *(data-s);
+ }
}
}
}