xref: /external/mesa3d/src/gallium/drivers/r300/compiler/radeon_inline_literals.c

#include "radeon_compiler.h"
#include "radeon_compiler_util.h"
#include "radeon_dataflow.h"
#include "radeon_program.h"
#include "radeon_program_constants.h"
#include <stdio.h>

#define VERBOSE 0

#define DBG(...) do { if (VERBOSE) fprintf(stderr, __VA_ARGS__); } while(0)

/* IEEE-754:
 * 22:0 mantissa
 * 30:23 exponent
 * 31 sign
 *
 * R300:
 * 0:2 mantissa
 * 3:6 exponent (bias 7)
 */
static int ieee_754_to_r300_float(float f, unsigned char *r300_float_out)
{
	unsigned float_bits = *((unsigned *)&f);
	/* XXX: Handle big-endian */
	unsigned mantissa = float_bits &         0x007fffff;
	unsigned biased_exponent = (float_bits & 0x7f800000) >> 23;
	unsigned negate = !!(float_bits &         0x80000000);
	int exponent = biased_exponent - 127;
	unsigned mantissa_mask = 0xff8fffff;
	unsigned r300_exponent, r300_mantissa;

	DBG("Converting %f (0x%x) to 7-bit:\n", f, float_bits);
	DBG("Raw exponent = %d\n", exponent);

	if (exponent < -7 || exponent > 8) {
		DBG("Failed exponent out of range\n\n");
		return 0;
	}

	if (mantissa & mantissa_mask) {
		DBG("Failed mantisa has too many bits:\n"
			"manitssa=0x%x mantissa_mask=0x%x, and=0x%x\n\n",
			mantissa, mantissa_mask,
			mantissa & mantissa_mask);
		return 0;
	}

	r300_exponent = exponent + 7;
	r300_mantissa = (mantissa & ~mantissa_mask) >> 20;
	*r300_float_out = r300_mantissa | (r300_exponent << 3);

	DBG("Success! r300_float = 0x%x\n\n", *r300_float_out);

	if (negate)
		return -1;
	else
		return 1;
}

void rc_inline_literals(struct radeon_compiler *c, void *user)
{
	struct rc_instruction * inst;

	for(inst = c->Program.Instructions.Next;
					inst != &c->Program.Instructions;
					inst = inst->Next) {
		const struct rc_opcode_info * info =
					rc_get_opcode_info(inst->U.I.Opcode);

		unsigned src_idx;
		struct rc_constant * constant;
		float float_value;
		unsigned char r300_float = 0;
		int ret;

		/* XXX: Handle presub */

		/* We aren't using rc_for_all_reads_src here, because presub
		 * sources need to be handled differently. */
		for (src_idx = 0; src_idx < info->NumSrcRegs; src_idx++) {
			unsigned new_swizzle;
			unsigned use_literal = 0;
			unsigned negate_mask = 0;
			unsigned swz, chan;
			struct rc_src_register * src_reg =
						&inst->U.I.SrcReg[src_idx];
			swz = RC_SWIZZLE_UNUSED;
			if (src_reg->File != RC_FILE_CONSTANT) {
				continue;
			}
			constant =
				&c->Program.Constants.Constants[src_reg->Index];
			if (constant->Type != RC_CONSTANT_IMMEDIATE) {
				continue;
			}
			new_swizzle = rc_init_swizzle(RC_SWIZZLE_UNUSED, 0);
			for (chan = 0; chan < 4; chan++) {
				unsigned char r300_float_tmp;
				swz = GET_SWZ(src_reg->Swizzle, chan);
				if (swz == RC_SWIZZLE_UNUSED) {
					continue;
				}
				float_value = constant->u.Immediate[swz];
				ret = ieee_754_to_r300_float(float_value,
								&r300_float_tmp);
				if (!ret || (use_literal &&
						r300_float != r300_float_tmp)) {
					use_literal = 0;
					break;
				}

				if (ret == -1 && src_reg->Abs) {
					use_literal = 0;
					break;
				}

				if (!use_literal) {
					r300_float = r300_float_tmp;
					use_literal = 1;
				}

				/* Use RC_SWIZZLE_W for the inline constant, so
				 * it will become one of the alpha sources. */
				SET_SWZ(new_swizzle, chan, RC_SWIZZLE_W);
				if (ret == -1) {
					negate_mask |= (1 << chan);
				}
			}

			if (!use_literal) {
				continue;
			}
			src_reg->File = RC_FILE_INLINE;
			src_reg->Index = r300_float;
			src_reg->Swizzle = new_swizzle;
			src_reg->Negate = src_reg->Negate ^ negate_mask;
		}
	}
}