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[915] Fix COS function using same plan as SIN.

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The previous COS function failed badly outside of [-pi/2, pi/2].
This commit is contained in:
Eric Anholt
2008-02-06 15:41:04 -08:00
parent 2551a5ee80
commit 700a77fb48
1 changed files with 63 additions and 35 deletions
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98
src/mesa/drivers/dri/i915/i915_fragprog.c
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@@ -48,7 +48,7 @@ static const GLfloat sin_quad_constants[2][4] = {
2.0,
-1.0,
.5,
0.0
.75
},
{
4.0,
@@ -375,52 +375,80 @@ upload_program(struct i915_fragment_program *p)
case OPCODE_COS:
src0 = src_vector(p, &inst->SrcReg[0], program);
tmp = i915_get_utemp(p);
consts0 = i915_emit_const4fv(p, sin_quad_constants[0]);
consts1 = i915_emit_const4fv(p, sin_quad_constants[1]);
/* Reduce range from repeating about [-pi,pi] to [-1,1] */
i915_emit_arith(p,
A0_MUL,
A0_MAD,
tmp, A0_DEST_CHANNEL_X, 0,
src0, i915_emit_const1f(p, 1.0 / (M_PI)), 0);
src0,
swizzle(consts1, Z, ZERO, ZERO, ZERO), /* 1/(2pi) */
swizzle(consts0, W, ZERO, ZERO, ZERO)); /* .75 */
i915_emit_arith(p, A0_MOD, tmp, A0_DEST_CHANNEL_X, 0, tmp, 0, 0);
i915_emit_arith(p, A0_FRC, tmp, A0_DEST_CHANNEL_X, 0, tmp, 0, 0);
/* By choosing different taylor constants, could get rid of this mul:
*/
i915_emit_arith(p,
A0_MAD,
tmp, A0_DEST_CHANNEL_X, 0,
tmp,
swizzle(consts0, X, ZERO, ZERO, ZERO), /* 2 */
swizzle(consts0, Y, ZERO, ZERO, ZERO)); /* -1 */
/* Compute COS with the same calculation used for SIN, but a
* different source range has been mapped to [-1,1] this time.
*/
/* tmp.y = abs(tmp.x); {x, abs(x), 0, 0} */
i915_emit_arith(p,
A0_MAX,
tmp, A0_DEST_CHANNEL_Y, 0,
swizzle(tmp, ZERO, X, ZERO, ZERO),
negate(swizzle(tmp, ZERO, X, ZERO, ZERO), 0, 1, 0, 0),
0);
/* tmp.y = tmp.y * tmp.x; {x, x * abs(x), 0, 0} */
i915_emit_arith(p,
A0_MUL,
tmp, A0_DEST_CHANNEL_Y, 0,
swizzle(tmp, ZERO, X, ZERO, ZERO),
tmp,
0);
/* tmp.x = tmp.xy DP sin_quad_constants[2].xy */
i915_emit_arith(p,
A0_MUL,
A0_DP3,
tmp, A0_DEST_CHANNEL_X, 0,
tmp, i915_emit_const1f(p, (M_PI)), 0);
tmp,
swizzle(consts1, X, Y, ZERO, ZERO),
0);
/*
* t0.xy = MUL x.xx11, x.x1111 ; x^2, x, 1, 1
* t0 = MUL t0.xyxy t0.xx11 ; x^4, x^3, x^2, 1
* t0 = MUL t0.xxz1 t0.z111 ; x^6 x^4 x^2 1
* result = DP4 t0, cos_constants
*/
i915_emit_arith(p,
A0_MUL,
tmp, A0_DEST_CHANNEL_XY, 0,
swizzle(tmp, X, X, ONE, ONE),
swizzle(tmp, X, ONE, ONE, ONE), 0);
/* tmp.x now contains a first approximation (y). Now, weight it
* against tmp.y**2 to get closer.
*/
i915_emit_arith(p,
A0_MAX,
tmp, A0_DEST_CHANNEL_Y, 0,
swizzle(tmp, ZERO, X, ZERO, ZERO),
negate(swizzle(tmp, ZERO, X, ZERO, ZERO), 0, 1, 0, 0),
0);
i915_emit_arith(p,
A0_MUL,
tmp, A0_DEST_CHANNEL_XYZ, 0,
swizzle(tmp, X, Y, X, ONE),
swizzle(tmp, X, X, ONE, ONE), 0);
/* tmp.y = tmp.x * tmp.y - tmp.x; {y, y * abs(y) - y, 0, 0} */
i915_emit_arith(p,
A0_MAD,
tmp, A0_DEST_CHANNEL_Y, 0,
swizzle(tmp, ZERO, X, ZERO, ZERO),
swizzle(tmp, ZERO, Y, ZERO, ZERO),
negate(swizzle(tmp, ZERO, X, ZERO, ZERO), 0, 1, 0, 0));
i915_emit_arith(p,
A0_MUL,
tmp, A0_DEST_CHANNEL_XYZ, 0,
swizzle(tmp, X, X, Z, ONE),
swizzle(tmp, Z, ONE, ONE, ONE), 0);
i915_emit_arith(p,
A0_DP4,
/* result = .2225 * tmp.y + tmp.x =.2225(y * abs(y) - y) + y= */
i915_emit_arith(p,
A0_MAD,
get_result_vector(p, inst),
get_result_flags(inst), 0,
swizzle(tmp, ONE, Z, Y, X),
i915_emit_const4fv(p, cos_constants), 0);
swizzle(consts1, W, W, W, W),
swizzle(tmp, Y, Y, Y, Y),
swizzle(tmp, X, X, X, X));
break;
case OPCODE_DP3: