diff options
Diffstat (limited to 'drivers/staging/brcm80211/brcmsmac/phy/phy_qmath.c')
-rw-r--r-- | drivers/staging/brcm80211/brcmsmac/phy/phy_qmath.c | 172 |
1 files changed, 93 insertions, 79 deletions
diff --git a/drivers/staging/brcm80211/brcmsmac/phy/phy_qmath.c b/drivers/staging/brcm80211/brcmsmac/phy/phy_qmath.c index 01ff0c8eb4b..faf1ebe7606 100644 --- a/drivers/staging/brcm80211/brcmsmac/phy/phy_qmath.c +++ b/drivers/staging/brcm80211/brcmsmac/phy/phy_qmath.c @@ -17,89 +17,95 @@ #include "phy_qmath.h" /* -Description: This function make 16 bit unsigned multiplication. To fit the output into -16 bits the 32 bit multiplication result is right shifted by 16 bits. -*/ + * Description: This function make 16 bit unsigned multiplication. + * To fit the output into 16 bits the 32 bit multiplication result is right + * shifted by 16 bits. + */ u16 qm_mulu16(u16 op1, u16 op2) { return (u16) (((u32) op1 * (u32) op2) >> 16); } /* -Description: This function make 16 bit multiplication and return the result in 16 bits. -To fit the multiplication result into 16 bits the multiplication result is right shifted by -15 bits. Right shifting 15 bits instead of 16 bits is done to remove the extra sign bit formed -due to the multiplication. -When both the 16bit inputs are 0x8000 then the output is saturated to 0x7fffffff. -*/ + * Description: This function make 16 bit multiplication and return the result + * in 16 bits. To fit the multiplication result into 16 bits the multiplication + * result is right shifted by 15 bits. Right shifting 15 bits instead of 16 bits + * is done to remove the extra sign bit formed due to the multiplication. + * When both the 16bit inputs are 0x8000 then the output is saturated to + * 0x7fffffff. + */ s16 qm_muls16(s16 op1, s16 op2) { s32 result; - if (op1 == (s16) 0x8000 && op2 == (s16) 0x8000) { + if (op1 == (s16) 0x8000 && op2 == (s16) 0x8000) result = 0x7fffffff; - } else { + else result = ((s32) (op1) * (s32) (op2)); - } + return (s16) (result >> 15); } /* -Description: This function add two 32 bit numbers and return the 32bit result. -If the result overflow 32 bits, the output will be saturated to 32bits. -*/ + * Description: This function add two 32 bit numbers and return the 32bit + * result. If the result overflow 32 bits, the output will be saturated to + * 32bits. + */ s32 qm_add32(s32 op1, s32 op2) { s32 result; result = op1 + op2; - if (op1 < 0 && op2 < 0 && result > 0) { + if (op1 < 0 && op2 < 0 && result > 0) result = 0x80000000; - } else if (op1 > 0 && op2 > 0 && result < 0) { + else if (op1 > 0 && op2 > 0 && result < 0) result = 0x7fffffff; - } + return result; } /* -Description: This function add two 16 bit numbers and return the 16bit result. -If the result overflow 16 bits, the output will be saturated to 16bits. -*/ + * Description: This function add two 16 bit numbers and return the 16bit + * result. If the result overflow 16 bits, the output will be saturated to + * 16bits. + */ s16 qm_add16(s16 op1, s16 op2) { s16 result; s32 temp = (s32) op1 + (s32) op2; - if (temp > (s32) 0x7fff) { + if (temp > (s32) 0x7fff) result = (s16) 0x7fff; - } else if (temp < (s32) 0xffff8000) { + else if (temp < (s32) 0xffff8000) result = (s16) 0xffff8000; - } else { + else result = (s16) temp; - } + return result; } /* -Description: This function make 16 bit subtraction and return the 16bit result. -If the result overflow 16 bits, the output will be saturated to 16bits. -*/ + * Description: This function make 16 bit subtraction and return the 16bit + * result. If the result overflow 16 bits, the output will be saturated to + * 16bits. + */ s16 qm_sub16(s16 op1, s16 op2) { s16 result; s32 temp = (s32) op1 - (s32) op2; - if (temp > (s32) 0x7fff) { + if (temp > (s32) 0x7fff) result = (s16) 0x7fff; - } else if (temp < (s32) 0xffff8000) { + else if (temp < (s32) 0xffff8000) result = (s16) 0xffff8000; - } else { + else result = (s16) temp; - } + return result; } /* -Description: This function make a 32 bit saturated left shift when the specified shift -is +ve. This function will make a 32 bit right shift when the specified shift is -ve. -This function return the result after shifting operation. -*/ + * Description: This function make a 32 bit saturated left shift when the + * specified shift is +ve. This function will make a 32 bit right shift when + * the specified shift is -ve. This function return the result after shifting + * operation. + */ s32 qm_shl32(s32 op, int shift) { int i; @@ -110,20 +116,21 @@ s32 qm_shl32(s32 op, int shift) else if (shift < -31) shift = -31; if (shift >= 0) { - for (i = 0; i < shift; i++) { + for (i = 0; i < shift; i++) result = qm_add32(result, result); - } } else { result = result >> (-shift); } + return result; } /* -Description: This function make a 16 bit saturated left shift when the specified shift -is +ve. This function will make a 16 bit right shift when the specified shift is -ve. -This function return the result after shifting operation. -*/ + * Description: This function make a 16 bit saturated left shift when the + * specified shift is +ve. This function will make a 16 bit right shift when + * the specified shift is -ve. This function return the result after shifting + * operation. + */ s16 qm_shl16(s16 op, int shift) { int i; @@ -134,29 +141,29 @@ s16 qm_shl16(s16 op, int shift) else if (shift < -15) shift = -15; if (shift > 0) { - for (i = 0; i < shift; i++) { + for (i = 0; i < shift; i++) result = qm_add16(result, result); - } } else { result = result >> (-shift); } + return result; } /* -Description: This function make a 16 bit right shift when shift is +ve. -This function make a 16 bit saturated left shift when shift is -ve. This function -return the result of the shift operation. -*/ + * Description: This function make a 16 bit right shift when shift is +ve. + * This function make a 16 bit saturated left shift when shift is -ve. This + * function return the result of the shift operation. + */ s16 qm_shr16(s16 op, int shift) { return qm_shl16(op, -shift); } /* -Description: This function return the number of redundant sign bits in a 32 bit number. -Example: qm_norm32(0x00000080) = 23 -*/ + * Description: This function return the number of redundant sign bits in a + * 32 bit number. Example: qm_norm32(0x00000080) = 23 + */ s16 qm_norm32(s32 op) { u16 u16extraSignBits; @@ -208,28 +215,30 @@ static const s16 log_table[] = { 32024 }; -#define LOG_TABLE_SIZE 32 /* log_table size */ -#define LOG2_LOG_TABLE_SIZE 5 /* log2(log_table size) */ -#define Q_LOG_TABLE 15 /* qformat of log_table */ -#define LOG10_2 19728 /* log10(2) in q.16 */ +#define LOG_TABLE_SIZE 32 /* log_table size */ +#define LOG2_LOG_TABLE_SIZE 5 /* log2(log_table size) */ +#define Q_LOG_TABLE 15 /* qformat of log_table */ +#define LOG10_2 19728 /* log10(2) in q.16 */ /* -Description: -This routine takes the input number N and its q format qN and compute -the log10(N). This routine first normalizes the input no N. Then N is in mag*(2^x) format. -mag is any number in the range 2^30-(2^31 - 1). Then log2(mag * 2^x) = log2(mag) + x is computed. -From that log10(mag * 2^x) = log2(mag * 2^x) * log10(2) is computed. -This routine looks the log2 value in the table considering LOG2_LOG_TABLE_SIZE+1 MSBs. -As the MSB is always 1, only next LOG2_OF_LOG_TABLE_SIZE MSBs are used for table lookup. -Next 16 MSBs are used for interpolation. -Inputs: -N - number to which log10 has to be found. -qN - q format of N -log10N - address where log10(N) will be written. -qLog10N - address where log10N qformat will be written. -Note/Problem: -For accurate results input should be in normalized or near normalized form. -*/ + * Description: + * This routine takes the input number N and its q format qN and compute + * the log10(N). This routine first normalizes the input no N. Then N is in + * mag*(2^x) format. mag is any number in the range 2^30-(2^31 - 1). + * Then log2(mag * 2^x) = log2(mag) + x is computed. From that + * log10(mag * 2^x) = log2(mag * 2^x) * log10(2) is computed. + * This routine looks the log2 value in the table considering + * LOG2_LOG_TABLE_SIZE+1 MSBs. As the MSB is always 1, only next + * LOG2_OF_LOG_TABLE_SIZE MSBs are used for table lookup. Next 16 MSBs are used + * for interpolation. + * Inputs: + * N - number to which log10 has to be found. + * qN - q format of N + * log10N - address where log10(N) will be written. + * qLog10N - address where log10N qformat will be written. + * Note/Problem: + * For accurate results input should be in normalized or near normalized form. + */ void qm_log10(s32 N, s16 qN, s16 *log10N, s16 *qLog10N) { s16 s16norm, s16tableIndex, s16errorApproximation; @@ -248,12 +257,13 @@ void qm_log10(s32 N, s16 qN, s16 *log10N, s16 *qLog10N) */ qN = qN + s16norm - 30; - /* take the table index as the LOG2_OF_LOG_TABLE_SIZE bits right of the MSB */ + /* take the table index as the LOG2_OF_LOG_TABLE_SIZE bits right of the + * MSB */ s16tableIndex = (s16) (N >> (32 - (2 + LOG2_LOG_TABLE_SIZE))); /* remove the MSB. the MSB is always 1 after normalization. */ s16tableIndex = - s16tableIndex & (s16) ((1 << LOG2_LOG_TABLE_SIZE) - 1); + s16tableIndex & (s16) ((1 << LOG2_LOG_TABLE_SIZE) - 1); /* remove the (1+LOG2_OF_LOG_TABLE_SIZE) MSBs in the N. */ N = N & ((1 << (32 - (2 + LOG2_LOG_TABLE_SIZE))) - 1); @@ -263,23 +273,27 @@ void qm_log10(s32 N, s16 qN, s16 *log10N, s16 *qLog10N) u16offset = (u16) (N >> (32 - (2 + LOG2_LOG_TABLE_SIZE + 16))); /* look the log value in the table. */ - s32log = log_table[s16tableIndex]; /* q.15 format */ + s32log = log_table[s16tableIndex]; /* q.15 format */ - /* interpolate using the offset. */ - s16errorApproximation = (s16) qm_mulu16(u16offset, (u16) (log_table[s16tableIndex + 1] - log_table[s16tableIndex])); /* q.15 */ + /* interpolate using the offset. q.15 format. */ + s16errorApproximation = (s16) qm_mulu16(u16offset, + (u16) (log_table[s16tableIndex + 1] - + log_table[s16tableIndex])); - s32log = qm_add16((s16) s32log, s16errorApproximation); /* q.15 format */ + /* q.15 format */ + s32log = qm_add16((s16) s32log, s16errorApproximation); /* adjust for the qformat of the N as * log2(mag * 2^x) = log2(mag) + x */ - s32log = qm_add32(s32log, ((s32) -qN) << 15); /* q.15 format */ + s32log = qm_add32(s32log, ((s32) -qN) << 15); /* q.15 format */ /* normalize the result. */ s16norm = qm_norm32(s32log); /* bring all the important bits into lower 16 bits */ - s32log = qm_shl32(s32log, s16norm - 16); /* q.15+s16norm-16 format */ + /* q.15+s16norm-16 format */ + s32log = qm_shl32(s32log, s16norm - 16); /* compute the log10(N) by multiplying log2(N) with log10(2). * as log10(mag * 2^x) = log2(mag * 2^x) * log10(2) |