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stm32: Use hardware double sqrt on F7/H7 MCUs. 

Identical to cd527bb324 but for doubles.
This gives a -2.754% improvement on bm_float.py, and -35% improvement on
calling sqrt in a loop.
This commit is contained in:
Jim Mussared 2019-10-09 22:59:35 +11:00 committed by Damien George
parent 305f537bf9
commit 580a2656d1
2 changed files with 15 additions and 1 deletions
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10
lib/libm_dbl/thumb_vfp_sqrt.c Normal file
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@ -0,0 +1,10 @@
// an implementation of sqrt for Thumb using hardware double-precision VFP instructions
double sqrt(double x) {
double ret;
asm volatile (
"vsqrt.f64 %P0, %P1\n"
: "=w" (ret)
: "w" (x));
return ret;
}

6
ports/stm32/Makefile
View File

@ -173,12 +173,16 @@ SRC_LIBM = $(addprefix lib/libm_dbl/,\
scalbn.c \ scalbn.c \
sin.c \ sin.c \
sinh.c \ sinh.c \
sqrt.c \
tan.c \ tan.c \
tanh.c \ tanh.c \
tgamma.c \ tgamma.c \
trunc.c \ trunc.c \
) )
ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f7 h7))
SRC_LIBM += lib/libm_dbl/thumb_vfp_sqrt.c
else
SRC_LIBM += lib/libm_dbl/sqrt.c
endif
else else
SRC_LIBM = $(addprefix lib/libm/,\ SRC_LIBM = $(addprefix lib/libm/,\
math.c \ math.c \