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| <a name="MIPS-DSP-Built_002din-Functions-1"></a> |
| <h4 class="subsection">6.57.14 MIPS DSP Built-in Functions</h4> |
| |
| <p>The MIPS DSP Application-Specific Extension (ASE) includes new |
| instructions that are designed to improve the performance of DSP and |
| media applications. It provides instructions that operate on packed |
| 8-bit/16-bit integer data, Q7, Q15 and Q31 fractional data. |
| </p> |
| <p>GCC supports MIPS DSP operations using both the generic |
| vector extensions (see <a href="Vector-Extensions.html#Vector-Extensions">Vector Extensions</a>) and a collection of |
| MIPS-specific built-in functions. Both kinds of support are |
| enabled by the <samp>-mdsp</samp> command-line option. |
| </p> |
| <p>Revision 2 of the ASE was introduced in the second half of 2006. |
| This revision adds extra instructions to the original ASE, but is |
| otherwise backwards-compatible with it. You can select revision 2 |
| using the command-line option <samp>-mdspr2</samp>; this option implies |
| <samp>-mdsp</samp>. |
| </p> |
| <p>The SCOUNT and POS bits of the DSP control register are global. The |
| WRDSP, EXTPDP, EXTPDPV and MTHLIP instructions modify the SCOUNT and |
| POS bits. During optimization, the compiler does not delete these |
| instructions and it does not delete calls to functions containing |
| these instructions. |
| </p> |
| <p>At present, GCC only provides support for operations on 32-bit |
| vectors. The vector type associated with 8-bit integer data is |
| usually called <code>v4i8</code>, the vector type associated with Q7 |
| is usually called <code>v4q7</code>, the vector type associated with 16-bit |
| integer data is usually called <code>v2i16</code>, and the vector type |
| associated with Q15 is usually called <code>v2q15</code>. They can be |
| defined in C as follows: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">typedef signed char v4i8 __attribute__ ((vector_size(4))); |
| typedef signed char v4q7 __attribute__ ((vector_size(4))); |
| typedef short v2i16 __attribute__ ((vector_size(4))); |
| typedef short v2q15 __attribute__ ((vector_size(4))); |
| </pre></div> |
| |
| <p><code>v4i8</code>, <code>v4q7</code>, <code>v2i16</code> and <code>v2q15</code> values are |
| initialized in the same way as aggregates. For example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">v4i8 a = {1, 2, 3, 4}; |
| v4i8 b; |
| b = (v4i8) {5, 6, 7, 8}; |
| |
| v2q15 c = {0x0fcb, 0x3a75}; |
| v2q15 d; |
| d = (v2q15) {0.1234 * 0x1.0p15, 0.4567 * 0x1.0p15}; |
| </pre></div> |
| |
| <p><em>Note:</em> The CPU’s endianness determines the order in which values |
| are packed. On little-endian targets, the first value is the least |
| significant and the last value is the most significant. The opposite |
| order applies to big-endian targets. For example, the code above |
| sets the lowest byte of <code>a</code> to <code>1</code> on little-endian targets |
| and <code>4</code> on big-endian targets. |
| </p> |
| <p><em>Note:</em> Q7, Q15 and Q31 values must be initialized with their integer |
| representation. As shown in this example, the integer representation |
| of a Q7 value can be obtained by multiplying the fractional value by |
| <code>0x1.0p7</code>. The equivalent for Q15 values is to multiply by |
| <code>0x1.0p15</code>. The equivalent for Q31 values is to multiply by |
| <code>0x1.0p31</code>. |
| </p> |
| <p>The table below lists the <code>v4i8</code> and <code>v2q15</code> operations for which |
| hardware support exists. <code>a</code> and <code>b</code> are <code>v4i8</code> values, |
| and <code>c</code> and <code>d</code> are <code>v2q15</code> values. |
| </p> |
| <table> |
| <tr><td width="50%">C code</td><td width="50%">MIPS instruction</td></tr> |
| <tr><td width="50%"><code>a + b</code></td><td width="50%"><code>addu.qb</code></td></tr> |
| <tr><td width="50%"><code>c + d</code></td><td width="50%"><code>addq.ph</code></td></tr> |
| <tr><td width="50%"><code>a - b</code></td><td width="50%"><code>subu.qb</code></td></tr> |
| <tr><td width="50%"><code>c - d</code></td><td width="50%"><code>subq.ph</code></td></tr> |
| </table> |
| |
| <p>The table below lists the <code>v2i16</code> operation for which |
| hardware support exists for the DSP ASE REV 2. <code>e</code> and <code>f</code> are |
| <code>v2i16</code> values. |
| </p> |
| <table> |
| <tr><td width="50%">C code</td><td width="50%">MIPS instruction</td></tr> |
| <tr><td width="50%"><code>e * f</code></td><td width="50%"><code>mul.ph</code></td></tr> |
| </table> |
| |
| <p>It is easier to describe the DSP built-in functions if we first define |
| the following types: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">typedef int q31; |
| typedef int i32; |
| typedef unsigned int ui32; |
| typedef long long a64; |
| </pre></div> |
| |
| <p><code>q31</code> and <code>i32</code> are actually the same as <code>int</code>, but we |
| use <code>q31</code> to indicate a Q31 fractional value and <code>i32</code> to |
| indicate a 32-bit integer value. Similarly, <code>a64</code> is the same as |
| <code>long long</code>, but we use <code>a64</code> to indicate values that are |
| placed in one of the four DSP accumulators (<code>$ac0</code>, |
| <code>$ac1</code>, <code>$ac2</code> or <code>$ac3</code>). |
| </p> |
| <p>Also, some built-in functions prefer or require immediate numbers as |
| parameters, because the corresponding DSP instructions accept both immediate |
| numbers and register operands, or accept immediate numbers only. The |
| immediate parameters are listed as follows. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">imm0_3: 0 to 3. |
| imm0_7: 0 to 7. |
| imm0_15: 0 to 15. |
| imm0_31: 0 to 31. |
| imm0_63: 0 to 63. |
| imm0_255: 0 to 255. |
| imm_n32_31: -32 to 31. |
| imm_n512_511: -512 to 511. |
| </pre></div> |
| |
| <p>The following built-in functions map directly to a particular MIPS DSP |
| instruction. Please refer to the architecture specification |
| for details on what each instruction does. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">v2q15 __builtin_mips_addq_ph (v2q15, v2q15) |
| v2q15 __builtin_mips_addq_s_ph (v2q15, v2q15) |
| q31 __builtin_mips_addq_s_w (q31, q31) |
| v4i8 __builtin_mips_addu_qb (v4i8, v4i8) |
| v4i8 __builtin_mips_addu_s_qb (v4i8, v4i8) |
| v2q15 __builtin_mips_subq_ph (v2q15, v2q15) |
| v2q15 __builtin_mips_subq_s_ph (v2q15, v2q15) |
| q31 __builtin_mips_subq_s_w (q31, q31) |
| v4i8 __builtin_mips_subu_qb (v4i8, v4i8) |
| v4i8 __builtin_mips_subu_s_qb (v4i8, v4i8) |
| i32 __builtin_mips_addsc (i32, i32) |
| i32 __builtin_mips_addwc (i32, i32) |
| i32 __builtin_mips_modsub (i32, i32) |
| i32 __builtin_mips_raddu_w_qb (v4i8) |
| v2q15 __builtin_mips_absq_s_ph (v2q15) |
| q31 __builtin_mips_absq_s_w (q31) |
| v4i8 __builtin_mips_precrq_qb_ph (v2q15, v2q15) |
| v2q15 __builtin_mips_precrq_ph_w (q31, q31) |
| v2q15 __builtin_mips_precrq_rs_ph_w (q31, q31) |
| v4i8 __builtin_mips_precrqu_s_qb_ph (v2q15, v2q15) |
| q31 __builtin_mips_preceq_w_phl (v2q15) |
| q31 __builtin_mips_preceq_w_phr (v2q15) |
| v2q15 __builtin_mips_precequ_ph_qbl (v4i8) |
| v2q15 __builtin_mips_precequ_ph_qbr (v4i8) |
| v2q15 __builtin_mips_precequ_ph_qbla (v4i8) |
| v2q15 __builtin_mips_precequ_ph_qbra (v4i8) |
| v2q15 __builtin_mips_preceu_ph_qbl (v4i8) |
| v2q15 __builtin_mips_preceu_ph_qbr (v4i8) |
| v2q15 __builtin_mips_preceu_ph_qbla (v4i8) |
| v2q15 __builtin_mips_preceu_ph_qbra (v4i8) |
| v4i8 __builtin_mips_shll_qb (v4i8, imm0_7) |
| v4i8 __builtin_mips_shll_qb (v4i8, i32) |
| v2q15 __builtin_mips_shll_ph (v2q15, imm0_15) |
| v2q15 __builtin_mips_shll_ph (v2q15, i32) |
| v2q15 __builtin_mips_shll_s_ph (v2q15, imm0_15) |
| v2q15 __builtin_mips_shll_s_ph (v2q15, i32) |
| q31 __builtin_mips_shll_s_w (q31, imm0_31) |
| q31 __builtin_mips_shll_s_w (q31, i32) |
| v4i8 __builtin_mips_shrl_qb (v4i8, imm0_7) |
| v4i8 __builtin_mips_shrl_qb (v4i8, i32) |
| v2q15 __builtin_mips_shra_ph (v2q15, imm0_15) |
| v2q15 __builtin_mips_shra_ph (v2q15, i32) |
| v2q15 __builtin_mips_shra_r_ph (v2q15, imm0_15) |
| v2q15 __builtin_mips_shra_r_ph (v2q15, i32) |
| q31 __builtin_mips_shra_r_w (q31, imm0_31) |
| q31 __builtin_mips_shra_r_w (q31, i32) |
| v2q15 __builtin_mips_muleu_s_ph_qbl (v4i8, v2q15) |
| v2q15 __builtin_mips_muleu_s_ph_qbr (v4i8, v2q15) |
| v2q15 __builtin_mips_mulq_rs_ph (v2q15, v2q15) |
| q31 __builtin_mips_muleq_s_w_phl (v2q15, v2q15) |
| q31 __builtin_mips_muleq_s_w_phr (v2q15, v2q15) |
| a64 __builtin_mips_dpau_h_qbl (a64, v4i8, v4i8) |
| a64 __builtin_mips_dpau_h_qbr (a64, v4i8, v4i8) |
| a64 __builtin_mips_dpsu_h_qbl (a64, v4i8, v4i8) |
| a64 __builtin_mips_dpsu_h_qbr (a64, v4i8, v4i8) |
| a64 __builtin_mips_dpaq_s_w_ph (a64, v2q15, v2q15) |
| a64 __builtin_mips_dpaq_sa_l_w (a64, q31, q31) |
| a64 __builtin_mips_dpsq_s_w_ph (a64, v2q15, v2q15) |
| a64 __builtin_mips_dpsq_sa_l_w (a64, q31, q31) |
| a64 __builtin_mips_mulsaq_s_w_ph (a64, v2q15, v2q15) |
| a64 __builtin_mips_maq_s_w_phl (a64, v2q15, v2q15) |
| a64 __builtin_mips_maq_s_w_phr (a64, v2q15, v2q15) |
| a64 __builtin_mips_maq_sa_w_phl (a64, v2q15, v2q15) |
| a64 __builtin_mips_maq_sa_w_phr (a64, v2q15, v2q15) |
| i32 __builtin_mips_bitrev (i32) |
| i32 __builtin_mips_insv (i32, i32) |
| v4i8 __builtin_mips_repl_qb (imm0_255) |
| v4i8 __builtin_mips_repl_qb (i32) |
| v2q15 __builtin_mips_repl_ph (imm_n512_511) |
| v2q15 __builtin_mips_repl_ph (i32) |
| void __builtin_mips_cmpu_eq_qb (v4i8, v4i8) |
| void __builtin_mips_cmpu_lt_qb (v4i8, v4i8) |
| void __builtin_mips_cmpu_le_qb (v4i8, v4i8) |
| i32 __builtin_mips_cmpgu_eq_qb (v4i8, v4i8) |
| i32 __builtin_mips_cmpgu_lt_qb (v4i8, v4i8) |
| i32 __builtin_mips_cmpgu_le_qb (v4i8, v4i8) |
| void __builtin_mips_cmp_eq_ph (v2q15, v2q15) |
| void __builtin_mips_cmp_lt_ph (v2q15, v2q15) |
| void __builtin_mips_cmp_le_ph (v2q15, v2q15) |
| v4i8 __builtin_mips_pick_qb (v4i8, v4i8) |
| v2q15 __builtin_mips_pick_ph (v2q15, v2q15) |
| v2q15 __builtin_mips_packrl_ph (v2q15, v2q15) |
| i32 __builtin_mips_extr_w (a64, imm0_31) |
| i32 __builtin_mips_extr_w (a64, i32) |
| i32 __builtin_mips_extr_r_w (a64, imm0_31) |
| i32 __builtin_mips_extr_s_h (a64, i32) |
| i32 __builtin_mips_extr_rs_w (a64, imm0_31) |
| i32 __builtin_mips_extr_rs_w (a64, i32) |
| i32 __builtin_mips_extr_s_h (a64, imm0_31) |
| i32 __builtin_mips_extr_r_w (a64, i32) |
| i32 __builtin_mips_extp (a64, imm0_31) |
| i32 __builtin_mips_extp (a64, i32) |
| i32 __builtin_mips_extpdp (a64, imm0_31) |
| i32 __builtin_mips_extpdp (a64, i32) |
| a64 __builtin_mips_shilo (a64, imm_n32_31) |
| a64 __builtin_mips_shilo (a64, i32) |
| a64 __builtin_mips_mthlip (a64, i32) |
| void __builtin_mips_wrdsp (i32, imm0_63) |
| i32 __builtin_mips_rddsp (imm0_63) |
| i32 __builtin_mips_lbux (void *, i32) |
| i32 __builtin_mips_lhx (void *, i32) |
| i32 __builtin_mips_lwx (void *, i32) |
| a64 __builtin_mips_ldx (void *, i32) [MIPS64 only] |
| i32 __builtin_mips_bposge32 (void) |
| a64 __builtin_mips_madd (a64, i32, i32); |
| a64 __builtin_mips_maddu (a64, ui32, ui32); |
| a64 __builtin_mips_msub (a64, i32, i32); |
| a64 __builtin_mips_msubu (a64, ui32, ui32); |
| a64 __builtin_mips_mult (i32, i32); |
| a64 __builtin_mips_multu (ui32, ui32); |
| </pre></div> |
| |
| <p>The following built-in functions map directly to a particular MIPS DSP REV 2 |
| instruction. Please refer to the architecture specification |
| for details on what each instruction does. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">v4q7 __builtin_mips_absq_s_qb (v4q7); |
| v2i16 __builtin_mips_addu_ph (v2i16, v2i16); |
| v2i16 __builtin_mips_addu_s_ph (v2i16, v2i16); |
| v4i8 __builtin_mips_adduh_qb (v4i8, v4i8); |
| v4i8 __builtin_mips_adduh_r_qb (v4i8, v4i8); |
| i32 __builtin_mips_append (i32, i32, imm0_31); |
| i32 __builtin_mips_balign (i32, i32, imm0_3); |
| i32 __builtin_mips_cmpgdu_eq_qb (v4i8, v4i8); |
| i32 __builtin_mips_cmpgdu_lt_qb (v4i8, v4i8); |
| i32 __builtin_mips_cmpgdu_le_qb (v4i8, v4i8); |
| a64 __builtin_mips_dpa_w_ph (a64, v2i16, v2i16); |
| a64 __builtin_mips_dps_w_ph (a64, v2i16, v2i16); |
| v2i16 __builtin_mips_mul_ph (v2i16, v2i16); |
| v2i16 __builtin_mips_mul_s_ph (v2i16, v2i16); |
| q31 __builtin_mips_mulq_rs_w (q31, q31); |
| v2q15 __builtin_mips_mulq_s_ph (v2q15, v2q15); |
| q31 __builtin_mips_mulq_s_w (q31, q31); |
| a64 __builtin_mips_mulsa_w_ph (a64, v2i16, v2i16); |
| v4i8 __builtin_mips_precr_qb_ph (v2i16, v2i16); |
| v2i16 __builtin_mips_precr_sra_ph_w (i32, i32, imm0_31); |
| v2i16 __builtin_mips_precr_sra_r_ph_w (i32, i32, imm0_31); |
| i32 __builtin_mips_prepend (i32, i32, imm0_31); |
| v4i8 __builtin_mips_shra_qb (v4i8, imm0_7); |
| v4i8 __builtin_mips_shra_r_qb (v4i8, imm0_7); |
| v4i8 __builtin_mips_shra_qb (v4i8, i32); |
| v4i8 __builtin_mips_shra_r_qb (v4i8, i32); |
| v2i16 __builtin_mips_shrl_ph (v2i16, imm0_15); |
| v2i16 __builtin_mips_shrl_ph (v2i16, i32); |
| v2i16 __builtin_mips_subu_ph (v2i16, v2i16); |
| v2i16 __builtin_mips_subu_s_ph (v2i16, v2i16); |
| v4i8 __builtin_mips_subuh_qb (v4i8, v4i8); |
| v4i8 __builtin_mips_subuh_r_qb (v4i8, v4i8); |
| v2q15 __builtin_mips_addqh_ph (v2q15, v2q15); |
| v2q15 __builtin_mips_addqh_r_ph (v2q15, v2q15); |
| q31 __builtin_mips_addqh_w (q31, q31); |
| q31 __builtin_mips_addqh_r_w (q31, q31); |
| v2q15 __builtin_mips_subqh_ph (v2q15, v2q15); |
| v2q15 __builtin_mips_subqh_r_ph (v2q15, v2q15); |
| q31 __builtin_mips_subqh_w (q31, q31); |
| q31 __builtin_mips_subqh_r_w (q31, q31); |
| a64 __builtin_mips_dpax_w_ph (a64, v2i16, v2i16); |
| a64 __builtin_mips_dpsx_w_ph (a64, v2i16, v2i16); |
| a64 __builtin_mips_dpaqx_s_w_ph (a64, v2q15, v2q15); |
| a64 __builtin_mips_dpaqx_sa_w_ph (a64, v2q15, v2q15); |
| a64 __builtin_mips_dpsqx_s_w_ph (a64, v2q15, v2q15); |
| a64 __builtin_mips_dpsqx_sa_w_ph (a64, v2q15, v2q15); |
| </pre></div> |
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