[Mesa-dev] [PATCH 26/53] st/nine: Correct LOG on negative values

[Axel Davy]

We should take the absolute value of the input.

Also return -FLT_MAX instead of -Inf for an input of 0.

Reviewed-by: David Heidelberg <david at ixit.cz>
Signed-off-by: Axel Davy <axel.davy at ens.fr>

Cc: "10.4" <mesa-stable at lists.freedesktop.org>
---
 src/gallium/state_trackers/nine/nine_shader.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/gallium/state_trackers/nine/nine_shader.c b/src/gallium/state_trackers/nine/nine_shader.c
index 48492b4..327dd2c 100644
--- a/src/gallium/state_trackers/nine/nine_shader.c
+++ b/src/gallium/state_trackers/nine/nine_shader.c
@@ -1968,6 +1968,17 @@ DECL_SPECIAL(RSQ)
     return D3D_OK;
 }
 
+DECL_SPECIAL(LOG)
+{
+    struct ureg_program *ureg = tx->ureg;
+    struct ureg_dst tmp = tx_scratch_scalar(tx);
+    struct ureg_dst dst = tx_dst_param(tx, &tx->insn.dst[0]);
+    struct ureg_src src = tx_src_param(tx, &tx->insn.src[0]);
+    ureg_LG2(ureg, tmp, ureg_abs(src));
+    ureg_MAX(ureg, dst, ureg_imm1f(ureg, -FLT_MAX), tx_src_scalar(tmp));
+    return D3D_OK;
+}
+
 DECL_SPECIAL(NRM)
 {
     struct ureg_program *ureg = tx->ureg;
@@ -2291,7 +2302,7 @@ struct sm1_op_info inst_table[] =
     _OPI(SLT, SLT, V(0,0), V(3,0), V(0,0), V(3,0), 1, 2, NULL), /* 12 */
     _OPI(SGE, SGE, V(0,0), V(3,0), V(0,0), V(3,0), 1, 2, NULL), /* 13 */
     _OPI(EXP, EX2, V(0,0), V(3,0), V(0,0), V(3,0), 1, 1, NULL), /* 14 */
-    _OPI(LOG, LG2, V(0,0), V(3,0), V(0,0), V(3,0), 1, 1, NULL), /* 15 */
+    _OPI(LOG, LG2, V(0,0), V(3,0), V(0,0), V(3,0), 1, 1, SPECIAL(LOG)), /* 15 */
     _OPI(LIT, LIT, V(0,0), V(3,0), V(0,0), V(0,0), 1, 1, NULL), /* 16 */
     _OPI(DST, DST, V(0,0), V(3,0), V(0,0), V(3,0), 1, 2, NULL), /* 17 */
     _OPI(LRP, LRP, V(0,0), V(3,0), V(0,0), V(3,0), 1, 3, NULL), /* 18 */
@@ -2355,7 +2366,7 @@ struct sm1_op_info inst_table[] =
 
     _OPI(EXPP, EXP, V(0,0), V(1,1), V(0,0), V(0,0), 1, 1, NULL),
     _OPI(EXPP, EX2, V(2,0), V(3,0), V(0,0), V(0,0), 1, 1, NULL),
-    _OPI(LOGP, LG2, V(0,0), V(3,0), V(0,0), V(0,0), 1, 1, NULL),
+    _OPI(LOGP, LG2, V(0,0), V(3,0), V(0,0), V(0,0), 1, 1, SPECIAL(LOG)),
     _OPI(CND,  NOP, V(0,0), V(0,0), V(0,0), V(1,4), 1, 3, SPECIAL(CND)),
 
     _OPI(DEF, NOP, V(0,0), V(3,0), V(0,0), V(3,0), 1, 0, SPECIAL(DEF)),
-- 
2.1.3