Space vector PWM and ASM translation

Hello,

I'm implementing Space Vector PWM in PBP in order to control with variable speed an 3-phase AC motor.

The base of my work is the AN955 from Microchip.
http://ww1.microchip.com/downloads/e...tes/00955a.pdf

In order to modify the output frequency, you have to modify the speed of the rotating vector Vs. (page 3)

So a "Degree_constant" is pre-defined (in my case 39)
The "Required_motor_speed" is in my case 50
So the "Vector_update_step_size" is 39*50=1950
And "Vector_angle"="Vector_angle"+1950

This is explained in page 8.

But I don't really understand the source code provided, especially that "Carry" thing (in ASM) :

Code:

;************************************************************************************* ;ISR FOR VECTOR ROTATION AND PHASE PWM DUTY CYCLE UPDATE ;************************************************************************************* ISR_PWM BCF PIR3,PTIF ;CLEAR PWM TIMER INTERUPT FLAG BTFSS ACSVM_FLAGS_1,FWD_REV BRA FIND_VECTOR_ANGLE_FOR_REV_DIR MOVFF PARAMETER_BUFFER+LOC_UPDATE_STEP_LSB,WREG ;INCREMENT VECTOR BY UPDATE STEP SIZE ADDWF VECTOR_ANGLE_LSB,F MOVFF PARAMETER_BUFFER+LOC_UPDATE_STEP_MSB,WREG ADDWFC VECTOR_ANGLE_MSB,F BNC READ_TIME_TB_COUNT ;DUE TO VECTOR INCREMENT, FOR CARRY = 0, CALCULATE CORRESPONDING TIME VALUES INCF SECTOR_NO,F ;DUE TO VECTOR INCREMENT, FOR CARRY = 1, INCREMENT SECTOR NO BRA CHECK_SECTOR_OF FIND_VECTOR_ANGLE_FOR_REV_DIR MOVFF PARAMETER_BUFFER+LOC_UPDATE_STEP_LSB,WREG SUBWF VECTOR_ANGLE_LSB,F MOVFF PARAMETER_BUFFER+LOC_UPDATE_STEP_MSB,WREG SUBWFB VECTOR_ANGLE_MSB,F BC READ_TIME_TB_COUNT INCF SECTOR_NO,F CHECK_SECTOR_OF MOVLW 0X05 CPFSGT SECTOR_NO BRA READ_TIME_TB_COUNT CLRF SECTOR_NO ;FOR SECTOR NO. ROLL OVER, REINITIALIZE SECTOR NO. TO 0 READ_TIME_TB_COUNT [...]

Can anyone would translate this ASM part of code in something more "PBPish"? :p

Thanks