CMSIS-DSP: problem with bitreversal2.s and arm_cfft_instance_q15

Hello everyone!

I am using an stm32L051 ( cortex M0+) to process a fft of a 256 points with the CMSIS-DSP V 1.4.5.

my problem is when i use the function arm_cfft_q15(), it remains blocked in the loop of the bitrevarsal_16 of the assembly code (bitrevarsal2.s) in this line LDR r4,[r6,#0].

I'm not sure of my instantiation with the structure arm_cfft_instance_q15.

define fftSize=256;
ifftFlag=0;
doBitReverse=1;

arm_cfft_instance_q15 arm_cfft_sR_q15_len256;
arm_cfft_sR_q15_len256.fftLen = (uint16_t) fftSize;
arm_cfft_sR_q15_len256.pTwiddle =(q15_t *)& twiddleCoef_256_q15;
arm_cfft_sR_q15_len256.bitRevLength =armBitRevIndexTable_fixed_256
arm_cfft_sR_q15_len256.pBitRevTable = (uint16_t *) & armBitRevTable[3];

arm_cfft_q15(&arm_cfft_sR_q15_len256, testInOutput_q15,ifftFlag, doBitReverse);

Appreciate any help in resolving these issues related to use of CMSIS DSP Lib on MDK Version 5 - Keil.

Oussbenj