[Mesa-dev] [PATCH 06/10] mesa: Prevent negative indexing on noise2, noise3 and noise4

[Juha-Pekka Heikkila]

% operator could return negative value which would cause
indexing before perm table.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
---
 src/mesa/program/prog_noise.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/mesa/program/prog_noise.c b/src/mesa/program/prog_noise.c
index c258c5e..12bb4d9 100644
--- a/src/mesa/program/prog_noise.c
+++ b/src/mesa/program/prog_noise.c
@@ -282,8 +282,8 @@ _mesa_noise2(GLfloat x, GLfloat y)
    y2 = y0 - 1.0f + 2.0f * G2;
 
    /* Wrap the integer indices at 256, to avoid indexing perm[] out of bounds */
-   ii = i % 256;
-   jj = j % 256;
+   ii = abs(i % 256);
+   jj = abs(j % 256);
 
    /* Calculate the contribution from the three corners */
    t0 = 0.5f - x0 * x0 - y0 * y0;
@@ -423,9 +423,9 @@ _mesa_noise3(GLfloat x, GLfloat y, GLfloat z)
    z3 = z0 - 1.0f + 3.0f * G3;
 
    /* Wrap the integer indices at 256 to avoid indexing perm[] out of bounds */
-   ii = i % 256;
-   jj = j % 256;
-   kk = k % 256;
+   ii = abs(i % 256);
+   jj = abs(j % 256);
+   kk = abs(k % 256);
 
    /* Calculate the contribution from the four corners */
    t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0;
@@ -573,10 +573,10 @@ _mesa_noise4(GLfloat x, GLfloat y, GLfloat z, GLfloat w)
    w4 = w0 - 1.0f + 4.0f * G4;
 
    /* Wrap the integer indices at 256, to avoid indexing perm[] out of bounds */
-   ii = i % 256;
-   jj = j % 256;
-   kk = k % 256;
-   ll = l % 256;
+   ii = abs(i % 256);
+   jj = abs(j % 256);
+   kk = abs(k % 256);
+   ll = abs(l % 256);
 
    /* Calculate the contribution from the five corners */
    t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0;
-- 
1.8.1.2