simple math operation error?

[ispd]

Dear Mr/Mrs,

I am debugging my code and I see that a simple operation is not done correctly:

eTPU->MCR.SCMSIZE = 9 and code size = 20480 so the result must be 0 and I see instead -$00004800

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uint32_t fs_etpu_init(struct etpu_config_t p_etpu_config, uint32_t *code,
                  uint32_t code_size, uint32_t *globals, uint32_t globals_size)
{
 uint32_t *code_end;
 int32_t unused_code_ram;
 int8_t x;

 unused_code_ram = ((eTPU->MCR.B.SCMSIZE + 1 ) * 2048) - code_size;
 if ( unused_code_ram < 0 ) return((uint32_t)FS_ETPU_ERROR_CODESIZE);

    /* 1. Load microcode */
    /* In order for the MISC function to work with code that is small than
       the code memory any unused locations must be set to zero. */
 /* enable writting to SCM */
 eTPU->ECR_A.B.MDIS = 1;    /* stop eTPU_A */
 eTPU->ECR_B.B.MDIS = 1;    /* stop eTPU_B */
 eTPU->MCR.B.VIS = 1;       /* enable CPU writes to eTPU code memory */

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[ispd]

i have checked that eTPU->MCR.B.SCMSIZE is "0" but when I see the debugger screen tells that it is '9'. How can this be possible if the header is ok?. Any idea?.