From 52608d2d21d401ac243d84409ec4043731a4f21a Mon Sep 17 00:00:00 2001 From: Keith Whitwell Date: Fri, 10 Jun 2005 08:32:27 +0000 Subject: Add notes about intended precision of opcodes. Remove dead floating point twiddles. Fix bug translating MAD->MUL,ADD. --- src/mesa/tnl/t_vb_arbprogram.c | 84 +++++++++++++++++++++++------------------- 1 file changed, 46 insertions(+), 38 deletions(-) (limited to 'src/mesa/tnl') diff --git a/src/mesa/tnl/t_vb_arbprogram.c b/src/mesa/tnl/t_vb_arbprogram.c index 4288bd3bef..457d56071e 100644 --- a/src/mesa/tnl/t_vb_arbprogram.c +++ b/src/mesa/tnl/t_vb_arbprogram.c @@ -61,45 +61,23 @@ struct compilation { #define ARB_VP_MACHINE(stage) ((struct arb_vp_machine *)(stage->privatePtr)) - - -/** - * Set x to positive or negative infinity. - * - * XXX: FIXME - type punning. - */ -#if defined(USE_IEEE) || defined(_WIN32) -#define SET_POS_INFINITY(x) ( *((GLuint *) (void *)&x) = 0x7F800000 ) -#define SET_NEG_INFINITY(x) ( *((GLuint *) (void *)&x) = 0xFF800000 ) -#elif defined(VMS) -#define SET_POS_INFINITY(x) x = __MAXFLOAT -#define SET_NEG_INFINITY(x) x = -__MAXFLOAT -#define IS_INF_OR_NAN(t) ((t) == __MAXFLOAT) -#else -#define SET_POS_INFINITY(x) x = (GLfloat) HUGE_VAL -#define SET_NEG_INFINITY(x) x = (GLfloat) -HUGE_VAL -#endif - -#define FREXPF(a,b) frexpf(a,b) - #define PUFF(x) ((x)[1] = (x)[2] = (x)[3] = (x)[0]) -/* FIXME: more type punning (despite use of fi_type...) - */ -#define SET_FLOAT_BITS(x, bits) ((fi_type *) (void *) &(x))->i = bits +/* Lower precision functions for the EXP, LOG and LIT opcodes. The + * LOG2() implementation is probably not accurate enough, and the + * attempted optimization for Exp2 is definitely not accurate + * enough - it discards all of t's fractional bits! + */ static GLfloat RoughApproxLog2(GLfloat t) { return LOG2(t); } -static GLfloat RoughApproxPow2(GLfloat t) +static GLfloat RoughApproxExp2(GLfloat t) { #if 0 - /* This isn't nearly accurate enough - it discards all of t's - * fractional bits! - */ fi_type fi; fi.i = (GLint) t; fi.i = (fi.i << 23) + 0x3f800000; @@ -111,11 +89,25 @@ static GLfloat RoughApproxPow2(GLfloat t) static GLfloat RoughApproxPower(GLfloat x, GLfloat y) { -#if 0 - return RoughApproxPow2(y * RoughApproxLog2(x)); -#else + return RoughApproxExp2(y * RoughApproxLog2(x)); +} + + +/* Higher precision functions for the EX2, LG2 and POW opcodes: + */ +static GLfloat ApproxLog2(GLfloat t) +{ + return (GLfloat) (log(t) * 1.442695F); +} + +static GLfloat ApproxExp2(GLfloat t) +{ + return (GLfloat) _mesa_pow(2.0, t); +} + +static GLfloat ApproxPower(GLfloat x, GLfloat y) +{ return (GLfloat) _mesa_pow(x, y); -#endif } @@ -261,15 +253,20 @@ static void do_DST( struct arb_vp_machine *m, union instruction op ) } +/* Intended to be high precision: + */ static void do_EX2( struct arb_vp_machine *m, union instruction op ) { GLfloat *result = m->File[0][op.alu.dst]; const GLfloat *arg0 = m->File[op.alu.file0][op.alu.idx0]; - result[0] = (GLfloat)RoughApproxPow2(arg0[0]); + result[0] = (GLfloat)ApproxExp2(arg0[0]); PUFF(result); } + +/* Allowed to be lower precision: + */ static void do_EXP( struct arb_vp_machine *m, union instruction op ) { GLfloat *result = m->File[0][op.alu.dst]; @@ -278,11 +275,11 @@ static void do_EXP( struct arb_vp_machine *m, union instruction op ) GLfloat flr_tmp = FLOORF(tmp); /* KW: nvvertexec has an optimized version of this which is pretty - * hard to understand/validate, but avoids the RoughApproxPow2. + * hard to understand/validate, but avoids the RoughApproxExp2. */ result[0] = (GLfloat) (1 << (int)flr_tmp); result[1] = tmp - flr_tmp; - result[2] = RoughApproxPow2(tmp); + result[2] = RoughApproxExp2(tmp); result[3] = 1.0F; } @@ -308,12 +305,14 @@ static void do_FRC( struct arb_vp_machine *m, union instruction op ) result[3] = arg0[3] - FLOORF(arg0[3]); } +/* High precision log base 2: + */ static void do_LG2( struct arb_vp_machine *m, union instruction op ) { GLfloat *result = m->File[0][op.alu.dst]; const GLfloat *arg0 = m->File[op.alu.file0][op.alu.idx0]; - result[0] = RoughApproxLog2(arg0[0]); + result[0] = ApproxLog2(arg0[0]); PUFF(result); } @@ -338,13 +337,15 @@ static void do_LIT( struct arb_vp_machine *m, union instruction op ) } +/* Intended to allow a lower precision than required for LG2 above. + */ static void do_LOG( struct arb_vp_machine *m, union instruction op ) { GLfloat *result = m->File[0][op.alu.dst]; const GLfloat *arg0 = m->File[op.alu.file0][op.alu.idx0]; GLfloat tmp = FABSF(arg0[0]); int exponent; - GLfloat mantissa = FREXPF(tmp, &exponent); + GLfloat mantissa = frexpf(tmp, &exponent); result[0] = (GLfloat) (exponent - 1); result[1] = 2.0 * mantissa; /* map [.5, 1) -> [1, 2) */ @@ -401,13 +402,15 @@ static void do_MUL( struct arb_vp_machine *m, union instruction op ) } +/* Intended to be "high" precision + */ static void do_POW( struct arb_vp_machine *m, union instruction op ) { GLfloat *result = m->File[0][op.alu.dst]; const GLfloat *arg0 = m->File[op.alu.file0][op.alu.idx0]; const GLfloat *arg1 = m->File[op.alu.file1][op.alu.idx1]; - result[0] = (GLfloat)RoughApproxPower(arg0[0], arg1[0]); + result[0] = (GLfloat)ApproxPower(arg0[0], arg1[0]); PUFF(result); } @@ -901,6 +904,11 @@ static void cvp_emit_inst( struct compilation *cp, op->alu.file1 = reg[2].file; op->alu.idx1 = reg[2].idx; op->alu.dst = result; + + if (result == REG_RES) { + op = cvp_next_instruction(cp); + op->dword = fixup.dword; + } break; case VP_OPCODE_ARL: -- cgit v1.2.3