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authorKeith Whitwell <keith@tungstengraphics.com>2008-05-26 11:03:00 +0100
committerKeith Whitwell <keith@tungstengraphics.com>2008-05-26 11:03:00 +0100
commit351eca365c0ba488000c3826d5093de6170381e4 (patch)
treeacf7bad1c6a02579efe0f144287accb047069c8e /src/gallium/auxiliary/draw/draw_vs_aos.c
parent721fb5597e687fc1446119002ab03cc428104b29 (diff)
draw: extend precision in RSQ opcode
Diffstat (limited to 'src/gallium/auxiliary/draw/draw_vs_aos.c')
-rw-r--r--src/gallium/auxiliary/draw/draw_vs_aos.c48
1 files changed, 27 insertions, 21 deletions
diff --git a/src/gallium/auxiliary/draw/draw_vs_aos.c b/src/gallium/auxiliary/draw/draw_vs_aos.c
index 916203c66b..1622358ae1 100644
--- a/src/gallium/auxiliary/draw/draw_vs_aos.c
+++ b/src/gallium/auxiliary/draw/draw_vs_aos.c
@@ -140,7 +140,8 @@ static void init_internals( struct aos_machine *machine )
ASSIGN_4V(machine->internal[IMM_NEGS], -1.0f, -1.0f, -1.0f, -1.0f);
ASSIGN_4V(machine->internal[IMM_IDENTITY], 0.0f, 0.0f, 0.0f, 1.0f);
ASSIGN_4V(machine->internal[IMM_INV_255], inv, inv, inv, inv);
- ASSIGN_4V(machine->internal[IMM_255], f255, f255, f255, f255);
+ ASSIGN_4V(machine->internal[IMM_255], f255, f255, f255, f255);
+ ASSIGN_4V(machine->internal[IMM_RSQ], -.5f, 1.5f, 0.0f, 0.0f);
machine->fpu_rnd_nearest = (X87_CW_EXCEPTION_INV_OP |
@@ -1561,35 +1562,40 @@ static boolean emit_RCP( struct aos_compilation *cp, const struct tgsi_full_inst
*
* x1 = 2 * rcpps(a) - a * rcpps(a) * rcpps(a)
* x1 = 0.5 * rsqrtps(a) * [3.0 - (a * rsqrtps(a))* rsqrtps(a)]
+ * or:
+ * x1 = rsqrtps(a) * [1.5 - .5 * a * rsqrtps(a) * rsqrtps(a)]
+ *
*
* See: http://softwarecommunity.intel.com/articles/eng/1818.htm
*/
static boolean emit_RSQ( struct aos_compilation *cp, const struct tgsi_full_instruction *op )
{
- struct x86_reg arg0 = fetch_src(cp, &op->FullSrcRegisters[0]);
- struct x86_reg dst = aos_get_xmm_reg(cp);
- if (1) {
- sse_rsqrtss(cp->func, dst, arg0);
+ if (0) {
+ struct x86_reg arg0 = fetch_src(cp, &op->FullSrcRegisters[0]);
+ struct x86_reg r = aos_get_xmm_reg(cp);
+ sse_rsqrtss(cp->func, r, arg0);
+ store_scalar_dest(cp, &op->FullDstRegisters[0], r);
+ return TRUE;
}
else {
-#if 0
- /* Extend precision here...
- */
- sse_movaps( func, dst, get_temp( TGSI_EXEC_TEMP_HALF_I, TGSI_EXEC_TEMP_HALF_C ) );
- sse_movaps( func, tmp0, get_temp( TGSI_EXEC_TEMP_THREE_I, TGSI_EXEC_TEMP_THREE_C ) );
-
- sse_rsqrtss( func, tmp1, src ); /* rsqrtss(a) */
- sse_mulss( func, src, tmp1 ); /* a * rsqrtss(a) */
- sse_mulss( func, dst, tmp1 ); /* .5 * rsqrtss(a) */
- sse_mulss( func, src, tmp1 ); /* a * rsqrtss(a) * rsqrtss(a) */
- sse_subss( func, tmp0, src ); /* 3.0 - (a * rsqrtss(a) * rsqrtss(a)) */
- sse_mulss( func, dst, tmp0 ); /* .5 * r * (3.0 - (a * r * r)) */
-#endif
- }
+ struct x86_reg arg0 = fetch_src(cp, &op->FullSrcRegisters[0]);
+ struct x86_reg r = aos_get_xmm_reg(cp);
- store_scalar_dest(cp, &op->FullDstRegisters[0], dst);
- return TRUE;
+ struct x86_reg neg_half = get_reg_ptr( cp, AOS_FILE_INTERNAL, IMM_RSQ );
+ struct x86_reg one_point_five = x86_make_disp( neg_half, 4 );
+ struct x86_reg src = get_xmm_writable( cp, arg0 );
+
+ sse_rsqrtss( cp->func, r, src ); /* rsqrtss(a) */
+ sse_mulss( cp->func, src, neg_half ); /* -.5 * a */
+ sse_mulss( cp->func, src, r ); /* -.5 * a * r */
+ sse_mulss( cp->func, src, r ); /* -.5 * a * r * r */
+ sse_addss( cp->func, src, one_point_five ); /* 1.5 - .5 * a * r * r */
+ sse_mulss( cp->func, r, src ); /* r * (1.5 - .5 * a * r * r) */
+
+ store_scalar_dest(cp, &op->FullDstRegisters[0], r);
+ return TRUE;
+ }
}