1 files changed, 60 insertions, 55 deletions

diff --git a/drivers/gpu/drm/radeon/r600_blit.c b/drivers/gpu/drm/radeon/r600_blit.c
index 3c031a48205d..661fec2a2cc1 100644
--- a/drivers/gpu/drm/radeon/r600_blit.c
+++ b/drivers/gpu/drm/radeon/r600_blit.c
@@ -489,31 +489,36 @@ set_default_state(drm_radeon_private_t *dev_priv)
         ADVANCE_RING();
 }
 
-static uint32_t i2f(uint32_t input)
+/* 23 bits of float fractional data */
+#define I2F_FRAC_BITS  23
+#define I2F_MASK ((1 << I2F_FRAC_BITS) - 1)
+
+/*
+ * Converts unsigned integer into 32-bit IEEE floating point representation.
+ * Will be exact from 0 to 2^24.  Above that, we round towards zero
+ * as the fractional bits will not fit in a float.  (It would be better to
+ * round towards even as the fpu does, but that is slower.)
+ */
+__pure uint32_t int2float(uint32_t x)
 {
-        u32 result, i, exponent, fraction;
-
-        if ((input & 0x3fff) == 0)
-                result = 0; /* 0 is a special case */
-        else {
-                exponent = 140; /* exponent biased by 127; */
-                fraction = (input & 0x3fff) << 10; /* cheat and only
-                                                      handle numbers below 2^^15 */
-                for (i = 0; i < 14; i++) {
-                        if (fraction & 0x800000)
-                                break;
-                        else {
-                                fraction = fraction << 1; /* keep
-                                                             shifting left until top bit = 1 */
-                                exponent = exponent - 1;
-                        }
-                }
-                result = exponent << 23 | (fraction & 0x7fffff); /* mask
-                                                                    off top bit; assumed 1 */
-        }
-        return result;
-}
+        uint32_t msb, exponent, fraction;
+
+        /* Zero is special */
+        if (!x) return 0;
+
+        /* Get location of the most significant bit */
+        msb = __fls(x);
 
+        /*
+         * Use a rotate instead of a shift because that works both leftwards
+         * and rightwards due to the mod(32) behaviour.  This means we don't
+         * need to check to see if we are above 2^24 or not.
+         */
+        fraction = ror32(x, (msb - I2F_FRAC_BITS) & 0x1f) & I2F_MASK;
+        exponent = (127 + msb) << I2F_FRAC_BITS;
+
+        return fraction + exponent;
+}
 
 static int r600_nomm_get_vb(struct drm_device *dev)
 {
@@ -632,20 +637,20 @@ r600_blit_copy(struct drm_device *dev,
                                 vb = r600_nomm_get_vb_ptr(dev);
                         }
 
-                        vb[0] = i2f(dst_x);
+                        vb[0] = int2float(dst_x);
                         vb[1] = 0;
-                        vb[2] = i2f(src_x);
+                        vb[2] = int2float(src_x);
                         vb[3] = 0;
 
-                        vb[4] = i2f(dst_x);
-                        vb[5] = i2f(h);
-                        vb[6] = i2f(src_x);
-                        vb[7] = i2f(h);
+                        vb[4] = int2float(dst_x);
+                        vb[5] = int2float(h);
+                        vb[6] = int2float(src_x);
+                        vb[7] = int2float(h);
 
-                        vb[8] = i2f(dst_x + cur_size);
-                        vb[9] = i2f(h);
-                        vb[10] = i2f(src_x + cur_size);
-                        vb[11] = i2f(h);
+                        vb[8] = int2float(dst_x + cur_size);
+                        vb[9] = int2float(h);
+                        vb[10] = int2float(src_x + cur_size);
+                        vb[11] = int2float(h);
 
                         /* src */
                         set_tex_resource(dev_priv, FMT_8,
@@ -721,20 +726,20 @@ r600_blit_copy(struct drm_device *dev,
                                 vb = r600_nomm_get_vb_ptr(dev);
                         }
 
-                        vb[0] = i2f(dst_x / 4);
+                        vb[0] = int2float(dst_x / 4);
                         vb[1] = 0;
-                        vb[2] = i2f(src_x / 4);
+                        vb[2] = int2float(src_x / 4);
                         vb[3] = 0;
 
-                        vb[4] = i2f(dst_x / 4);
-                        vb[5] = i2f(h);
-                        vb[6] = i2f(src_x / 4);
-                        vb[7] = i2f(h);
+                        vb[4] = int2float(dst_x / 4);
+                        vb[5] = int2float(h);
+                        vb[6] = int2float(src_x / 4);
+                        vb[7] = int2float(h);
 
-                        vb[8] = i2f((dst_x + cur_size) / 4);
-                        vb[9] = i2f(h);
-                        vb[10] = i2f((src_x + cur_size) / 4);
-                        vb[11] = i2f(h);
+                        vb[8] = int2float((dst_x + cur_size) / 4);
+                        vb[9] = int2float(h);
+                        vb[10] = int2float((src_x + cur_size) / 4);
+                        vb[11] = int2float(h);
 
                         /* src */
                         set_tex_resource(dev_priv, FMT_8_8_8_8,
@@ -804,20 +809,20 @@ r600_blit_swap(struct drm_device *dev,
         dx2 = dx + w;
         dy2 = dy + h;
 
-        vb[0] = i2f(dx);
-        vb[1] = i2f(dy);
-        vb[2] = i2f(sx);
-        vb[3] = i2f(sy);
+        vb[0] = int2float(dx);
+        vb[1] = int2float(dy);
+        vb[2] = int2float(sx);
+        vb[3] = int2float(sy);
 
-        vb[4] = i2f(dx);
-        vb[5] = i2f(dy2);
-        vb[6] = i2f(sx);
-        vb[7] = i2f(sy2);
+        vb[4] = int2float(dx);
+        vb[5] = int2float(dy2);
+        vb[6] = int2float(sx);
+        vb[7] = int2float(sy2);
 
-        vb[8] = i2f(dx2);
-        vb[9] = i2f(dy2);
-        vb[10] = i2f(sx2);
-        vb[11] = i2f(sy2);
+        vb[8] = int2float(dx2);
+        vb[9] = int2float(dy2);
+        vb[10] = int2float(sx2);
+        vb[11] = int2float(sy2);
 
         switch(cpp) {
         case 4: