Arduino for STM32

Code: Select all

  RCC_OscInitStruct.PLL.PLLM = 12;
  RCC_OscInitStruct.PLL.PLLN = 96;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLQ = 4;

Code: Select all

FHSE: 25 m: 25 n: 192 p: 2 (RCC_PLLP_DIV2) q: 4 fusb: 48.0 fcpu: 96.0
FHSE: 25 m: 25 n: 384 p: 4 (RCC_PLLP_DIV4) q: 8 fusb: 48.0 fcpu: 96.0
FHSE: 25 m: 25 n: 432 p: 4 (RCC_PLLP_DIV4) q: 9 fusb: 48.0 fcpu: 108.0
FHSE: 25 m: 50 n: 384 p: 2 (RCC_PLLP_DIV2) q: 4 fusb: 48.0 fcpu: 96.0

Code: Select all

-mcpu=cortex-m4 -march=armv7e-m+fp

Code: Select all

-O2
##########################################
Single Precision C Whetstone Benchmark
Calibrate
       0.10 Seconds          1   Passes (x 100)
       0.50 Seconds          5   Passes (x 100)
       2.48 Seconds         25   Passes (x 100)

Use 100  passes (x 100)

          Single Precision C/C++ Whetstone Benchmark
Loop content                  Result              MFLOPS      MOPS   Seconds

N1 floating point     -1.12475013732910156        46.489              0.041
N2 floating point     -1.12274742126464844        33.350              0.403
N3 if then else        1.00000000000000000                  95.833    0.108
N4 fixed point        12.00000000000000000                 159.898    0.197
N5 sin,cos etc.        0.49909299612045288                   2.260    3.681
N6 floating point      0.99999982118606567        35.960              1.500
N7 assignments         3.00000000000000000                  41.158    0.449
N8 exp,sqrt etc.       0.75110614299774170                   1.051    3.539

MWIPS                                            100.824              9.918


-O3

##########################################
Single Precision C Whetstone Benchmark
Calibrate
       0.10 Seconds          1   Passes (x 100)
       0.48 Seconds          5   Passes (x 100)
       2.40 Seconds         25   Passes (x 100)

Use 104  passes (x 100)

          Single Precision C/C++ Whetstone Benchmark
Loop content                  Result              MFLOPS      MOPS   Seconds

N1 floating point     -1.12475013732910156        48.000              0.042
N2 floating point     -1.12274742126464844        36.495              0.383
N3 if then else        1.00000000000000000                   0.000    0.000
N4 fixed point        12.00000000000000000                 180.000    0.182
N5 sin,cos etc.        0.49909299612045288                   2.358    3.670
N6 floating point      0.99999982118606567        33.875              1.656
N7 assignments         3.00000000000000000                  48.048    0.400
N8 exp,sqrt etc.       0.75110614299774170                   1.063    3.639

MWIPS                                            104.296              9.972

Code: Select all

-O2 (M4 - No -march=armv7e-m+fp)
##########################################
Single Precision C Whetstone Benchmark
Calibrate
       0.15 Seconds          1   Passes (x 100)
       0.77 Seconds          5   Passes (x 100)
       3.85 Seconds         25   Passes (x 100)

Use 64  passes (x 100)

          Single Precision C/C++ Whetstone Benchmark
Loop content                  Result              MFLOPS      MOPS   Seconds

N1 floating point     -1.12475013732910156        46.545              0.026
N2 floating point     -1.12274742126464844        33.340              0.258
N3 if then else        1.00000000000000000                  96.000    0.069
N4 fixed point        12.00000000000000000                 180.001    0.112
N5 sin,cos etc.        0.49909299612045288                   0.915    5.817
N6 floating point      0.99999982118606567        33.878              1.019
N7 assignments         3.00000000000000000                  41.210    0.287
N8 exp,sqrt etc.       0.75110614299774170                   1.051    2.265

MWIPS                                             64.952              9.853
[code]

Code: Select all

‘armv7e-m’

    ‘+fp’

        The single-precision VFPv4 floating-point instructions.
    ‘+fpv5’

        The single-precision FPv5 floating-point instructions.
    ‘+fp.dp’

        The single- and double-precision FPv5 floating-point instructions.
    ‘+nofp’

        Disable the floating-point extensions. 

Code: Select all

-mfpu=name

    This specifies what floating-point hardware (or hardware emulation) is available on the target. Permissible names are: ‘auto’, ‘vfpv2’, ‘vfpv3’, ‘vfpv3-fp16’, ‘vfpv3-d16’, ‘vfpv3-d16-fp16’, ‘vfpv3xd’, ‘vfpv3xd-fp16’, ‘neon-vfpv3’, ‘neon-fp16’, ‘vfpv4’, ‘vfpv4-d16’, ‘fpv4-sp-d16’, ‘neon-vfpv4’, ‘fpv5-d16’, ‘fpv5-sp-d16’, ‘fp-armv8’, ‘neon-fp-armv8’ and ‘crypto-neon-fp-armv8’. Note that ‘neon’ is an alias for ‘neon-vfpv3’ and ‘vfp’ is an alias for ‘vfpv2’.

    The setting ‘auto’ is the default and is special. It causes the compiler to select the floating-point and Advanced SIMD instructions based on the settings of -mcpu and -march.

    If the selected floating-point hardware includes the NEON extension (e.g. -mfpu=neon), note that floating-point operations are not generated by GCC’s auto-vectorization pass unless -funsafe-math-optimizations is also specified. This is because NEON hardware does not fully implement the IEEE 754 standard for floating-point arithmetic (in particular denormal values are treated as zero), so the use of NEON instructions may lead to a loss of precision.

    You can also set the fpu name at function level by using the target("fpu=") function attributes (see ARM Function Attributes) or pragmas (see Function Specific Option Pragmas).

Code: Select all

  n1 = 12 * x100;
  n2 = 14 * x100;
  n3 = 345 * x100;
  n4 = 210 * x100;
  n5 = 32 * x100;
  n6 = 899 * x100;
  n7 = 616 * x100;
  n8 = 93 * x100;
  n1mult = 10;

Code: Select all

-O
-O1
    Optimize. Optimizing compilation takes somewhat more time, and a lot more memory for a large function.

    With -O, the compiler tries to reduce code size and execution time, without performing any optimizations that take a great deal of compilation time.

    -O turns on the following optimization flags:

              -fauto-inc-dec 
              -fcompare-elim 
              -fcprop-registers 
              -fdce 
              -fdefer-pop 
              -fdelayed-branch 
              -fdse 
              -fguess-branch-probability 
              -fif-conversion2 
              -fif-conversion 
              -fipa-pure-const 
              -fipa-profile 
              -fipa-reference 
              -fmerge-constants
              -fsplit-wide-types 
              -ftree-bit-ccp 
              -ftree-builtin-call-dce 
              -ftree-ccp 
              -ftree-ch 
              -ftree-copyrename 
              -ftree-dce 
              -ftree-dominator-opts 
              -ftree-dse 
              -ftree-forwprop 
              -ftree-fre 
              -ftree-phiprop 
              -ftree-sra 
              -ftree-pta 
              -ftree-ter 
              -funit-at-a-time

    -O also turns on -fomit-frame-pointer on machines where doing so does not interfere with debugging.
-O2
    Optimize even more. GCC performs nearly all supported optimizations that do not involve a space-speed tradeoff. As compared to -O, this option increases both compilation time and the performance of the generated code.

    -O2 turns on all optimization flags specified by -O. It also turns on the following optimization flags:

              -fthread-jumps 
              -falign-functions  -falign-jumps 
              -falign-loops  -falign-labels 
              -fcaller-saves 
              -fcrossjumping 
              -fcse-follow-jumps  -fcse-skip-blocks 
              -fdelete-null-pointer-checks 
              -fdevirtualize 
              -fexpensive-optimizations 
              -fgcse  -fgcse-lm  
              -finline-small-functions 
              -findirect-inlining 
              -fipa-sra 
              -foptimize-sibling-calls 
              -fpartial-inlining 
              -fpeephole2 
              -fregmove 
              -freorder-blocks  -freorder-functions 
              -frerun-cse-after-loop  
              -fsched-interblock  -fsched-spec 
              -fschedule-insns  -fschedule-insns2 
              -fstrict-aliasing -fstrict-overflow 
              -ftree-switch-conversion -ftree-tail-merge 
              -ftree-pre 
              -ftree-vrp

    Please note the warning under -fgcse about invoking -O2 on programs that use computed gotos.
-O3
    Optimize yet more. -O3 turns on all optimizations specified by -O2 and also turns on the -finline-functions, -funswitch-loops, -fpredictive-commoning, -fgcse-after-reload, -ftree-vectorize and -fipa-cp-clone options.
-O0
    Reduce compilation time and make debugging produce the expected results. This is the default.
-Os
    Optimize for size. -Os enables all -O2 optimizations that do not typically increase code size. It also performs further optimizations designed to reduce code size.

    -Os disables the following optimization flags:

              -falign-functions  -falign-jumps  -falign-loops 
              -falign-labels  -freorder-blocks  -freorder-blocks-and-partition 
              -fprefetch-loop-arrays  -ftree-vect-loop-version